History

When Curran published the identification key to the Afrotropical species of the genus Dichaetomyia and the subgenus Panaga in 1935, he also pointed out that some species of this genus are probably still to be found in other genera, since various specimens of this genus had been assigned to other genera in previous years, before Malloch introduced the genus Dichaetomyia in 1921. In 1942, Emden then published an identification key which contained the already known Afrotropical Dichaetomyia species and, above all, the large number of new species he had discovered. This key has been used for the last 80 years to assign Dichaetomyia specimens of the Afrotropical Region to the appropriate taxa. The key also included the two similar species Dichaetomyia ovata and Dichaetomyia rutila, described by STEIN (1918). Although Stein mentioned a white median spot on the anterior mesonotum for both species in the descriptions, D. rutila and D. ovata were distinguished in Curran's identification key only by the absence or presence of a white spot on the presutural mesonotum, respectively. Emden, on the other hand, wrote for D. ovata var. rutila in his key: “Median dusted vitta often less distinct”. Also, like Stein, he pointed to the almost complete row of anteroventral setae on the hind femur of female D. ovata as a distinguishing feature. While Stein only mentioned two longer anteroventrals on the hind femur of females of D. rutila, Emden mentioned, for rutila, 2–5 setae for both sexes. However, increasing the number to five possible setae minimized the importance of this distinguishing feature, since in the female syntype of D. ovata the row of anteroventrals on the hind femur consists of only six strong setae. The larger number of setae and the inclusion of both sexes of D. rutila in the key was by no means supported by the species description, which was based on five females but no males. Thus, a key feature for distinguishing the two taxa had lost importance with Emden's definition, and a reliable assignment of specimens to one of the two taxa was no longer possible. Since one of the two female syntypes of D. ovata (PONT & WERNER 2006) and all five female types of D. rutila in the Budapest Museum were destroyed by fire in 1956 (PONT 2013), a detailed comparison of the two species was no longer possible. In addition, Stein's descriptions of the two species did not provide sufficient evidence that they are different taxa, and neither Curran nor Emden indicated in the supplementary characterizations of D. ovata and D. rutila that these were based on investigations of the type material. The two taxa have therefore been considered conspecific since the publication of the Catalogue of Afrotropical Muscidae (PONT 1980).

Using Emden's identification key, D. ovata specimens identified before 1980 were assigned to either D. ovata or “D. ovata rutila”, apparently without questioning the feebleness of the characters used to distinguish the two “taxa”. Corresponding examples can be seen also on the identification labels of specimens in the entomological collections of the Natural History Museum, London and of the Californian Academy of Sciences, San Francisco. In addition, some specimens of D. rutila are labelled by Emden himself in 1942 as D. ovata rutila. Only the recently conducted comparison of Malagasy Dichaetomyia material with type specimens of various taxa revealed a number of misidentifications (ZIELKE 2020). A similar phenomenon has now also been found in the widespread D. ovata. Some predominantly brownish yellow coloured specimens had, due to their similarity, been assigned to this species on the basis of the available identification keys. However, they are herein assessed as belonging to other species based on their specific combination of morphological characteristics.

Material examined

Syntype (♀) from Uganda (ZMB), with five small labels bearing the following inscriptions: 1. “Uganda Katona”; 2. “Mujenje 1913.VIII.”; 3. “Type 4. Mydaea ovata sp. n.”; 5. “Zool. Mus. Berlin”.

Remarks. According to PONT & WERNER (2006), this is one of the two syntypes on which Stein based his description. The female is in excellent condition.

Redescription

Female. Head. Ground colour mainly dark brown, depending on the incidence of light, with some parts greyish or densely silvery-white dusted (Fig. 1). Dichoptic; eyes practically bare, facets of about equal size. Frons slightly dilated towards the anterior margin, distance between eyes at vertex 0.27 times as wide as maximal width of head, at level of anterior ocellus about 4 times and at anterior margin of frons about 5.3 times as wide as the distance between the outer margins of the posterior ocelli. Fronto-orbital plate at midlength of frons almost as broad as distance between the outer margins of the posterior ocelli; frontal vitta slightly oval-shaped, at midlength about 3 times as wide as fronto-orbital plate, frontal triangle barely reaching middle of frons. Parafacial distinctly tapering, at level of base of antenna at least 1.5 times as wide as depth of postpedicel, at lower end about 1.5 times as wide as anterior ocellus. In profile, upper mouth margin in line with profrons; parafacial visible throughout its entire length; genal depth below lowest eye margin barely as broad as width of postpedicel (Fig. 2). When viewed anteriorly, fronto-orbital plates predominantly dark brown to black and more or less densely whitish-dusted depending on incidence of light, frontal vitta contrasting velvet dark brown, frontal triangle and ocellar tubercle dark, at some angles somewhat whitish-dusted, parafacial and anterior part of gena densely silvery-white dusted, ground colour of face pale yellow, at certain viewing angles densely white-dusted. Basal segments of antenna and base of postpedicel until insertion of arista strikingly yellow (Fig. 1), remaining part of postpedicel dark brown and greyish-dusted (Fig. 2). Postpedicel clearly longer than 3 times its depth and about twice as long as pedicel. Arista predominantly yellow, at least twice as long as postpedicel, longest hairs of arista about 1.5 times as long as depth of postpedicel. Anterior half of fronto-orbital plate with 4 setae, the anterior seta strong, the next one only half as long and the uppermost ones distinctly shorter and weaker, at midlength one or two very small hair-like setae, in upper half at level of anterior ocellus a strong reclinate orbital seta with another orbital seta slightly below it, about half as long as the upper one. Between eye margin and frontal and orbital setae some small proclinate setulae. Parafacial and facial ridge bare. Vibrissal setae strong and at least twice as long as the longest surrounding peristomal setae. Lateral surface of gena dark brown, at lower margin pale brown, weakly dusted and bare, margin of gena with a row of strong dark setae, post-occipital surface more greyish dusted and only sparsely covered with dark setulae. Proboscis slender, prementum yellowish brown and depending on incidence of light slightly whitish-dusted or shiny, labella almost twice as long as greatest depth of proboscis; palpus yellow (Fig. 2), slender, weakly clavate and about 1.5 times as long as prementum.

Thorax. Predominantly yellowish to brownish yellow (Figs. 3, 4). Mesonotum brownish yellow without dark pattern, depending on viewing angle shiny or partially whitish-dusted; in dorsal view postpronotum and notopleuron pale yellow, somewhat contrasting with brownish yellow mesonotum (Fig. 3). Presutural part of mesonotum with a median white-dusted stripe (Fig. 3), when viewed posteriorly tapering toward the transverse suture but not reaching it. Scutellum of about the same colour as mesonotum. Pleura shiny pale yellow, somewhat contrasting with darker yellow mesonotum (Fig. 4), when viewed directly anteriorly, partly whitish-dusted. Anterior and posterior spiracles pale yellow, posterior spiracle with dark setae at the lower margin. Mesonotum and dorsal lateral surfaces of scutellum covered with rather short black setulae, pleura predominantly bare or very sparsely covered with setulae. Acrostichals 0+1, at most half as long as the posterior dorsocentral seta; dorsocentral setae 2+3, the anterior presutural seta somewhat shorter than the other dorsocentrals; postpronotal setae 2, the outer seta clearly longer than the inner seta; notopleuron with about 3 small and fine setulae, anterior notopleural seta slightly longer than posterior one; prealar seta slightly shorter than posterior notopleural seta; 2 long intra-alar setae; supra-alar setae 2; postalar setae 3. Greater ampulla with several dark setulae, suprasquamal ridge bare. Prosternum with some dark hair-like setae; anepimeron in the upper part with a tuft of slightly longer, darker hairs and with a few scattered hairs on the lower part, about as long as or longer than the hairs of the tuft (Fig. 6); proepimeral area, meron and katepimeron bare. Katepisternal setae 1+2, the lower seta clearly closer to the posterior upper seta; anepisternal setae 1+5, all black and strong, dark interstitial hairs much weaker and about half as long as the setae. Scutellum with long apical and lateral setae, basal and preapical setae distinctly shorter but clearly distinguishable from ground hairs, ventral surface bare.

Wing. Membrane hyaline, with a brownish tinge (Fig. 4), cross-veins and surrounding membrane not infuscate. Stem vein yellow and somewhat contrasting with the subsequent brown parts of the veins, tegula and basicosta yellow. Costal spine at least twice as long as adjacent bristles but not very prominent. Radial node dorsally and ventrally bare, ventral part of vein R₄₊₅ with few small setae. Vein M somewhat diverging from vein R₄₊₅, but slightly curved forward toward R₄₊₅ before reaching wing margin. Cross-vein r-m slightly basad from the point where vein R₁ enters costa; distal cross-vein dm-cu almost sinuous and somewhat oblique. Both calypters yellowish shiny transparent, margins yellowish, lower calypter about 1.5 times as long as upper calypter. Stem and knob of haltere yellow.

Legs. Coxae, trochanters, femora, tibiae and tarsi yellow. Hind coxa bare on posterior surface. Pulvilli and claws well developed but at most half as long as the corresponding tarsomere. Fore femur with complete rows of posterodorsal, posterior and posteroventral setae, the posterodorsals and posteriors about as long as depth of femur, posteroventrals slightly longer. Fore tibia without a median posterior seta but with a distinct black short median anterodorsal seta. Basal half of mid femur with a row of about 4 dark ventral setae about half as long as depth of femur and a row of short bristle-like setae (Fig. 26) in the upper half of anterior surface, preapically with a row of about 6 short posteroventral seta-like hairs and 4 strong posterior to almost dorsal setae and a distinct anterodorsal seta. Mid tibia with 2 strong posterior setae, longer than diameter of tibia. Hind femur with an irregular but complete row of anterodorsal setae about as long as depth of femur, in apical half 3 anteroventral setae slightly longer than depth of femur, in basal half 2 anteroventral and 2 posteroventral setae and in addition a median anteroventral seta, all setae barely as long as depth of femur (Fig. 26), preapically a short row of seta-like posteroventral hairs barely half as long as depth of femur and 2 strong posterodorsal to dorsal setae. Hind tibia without a long posterodorsal seta, in distal half with an anterodorsal seta slightly longer than diameter of tibia and a shorter anteroventral seta barely as long as diameter of tibia, in addition with a short but clearly distinguishable posterodorsal seta about opposite to anteroventral seta.

Abdomen. Without specific pattern (Fig. 5) apart from anterior yellow part of syntergite 1+2 uniformly yellowish brownish without any dusting independent of viewing angle, in general somewhat darker than the thorax. Ventral parts of tergites and sternites practically concolourous with dorsal surface of tergites. Tergites densely covered with small black setulae, syntergite 1+2 and tergite 3 with a few longer marginals laterally, tergites 4 and 5 with a few marginals also dorsally but not in the median area, tergite 5 in addition with a few discal setae dorsolaterally but not as a complete row. Sternite 1: not only the margin but also parts of the surface anterior to the margin covered with dark setulae.

Genitalia not investigated.

Measurements. Body length 10.0 mm; wing length 9.5 mm.

Male unknown.]

Type material

Holotype ♂ from Liberia, with two labels: 1. The locality label “Liberia, Monrovia, VII-5-57, E. S. Ross & R. E. Leech collectors” and 2. The identification label “Dichaetomyia ovata rutila St. det E. Zielke 1972”.

Paratype: 1 ♂ with three small labels: 1. The registration number “CASENT8085403”, 2. The locality label “Liberia, 8 or 6 [not clearly readable] mi NW Fisebu, 12-VIII-1966 E. S. Ross & K. Lorenzen”, and 3. The identification label “Dichaetomyia ovata rutila St. det E. Zielke 1972”.

Remarks. The holotype is in very good condition; the paratype is missing the left mid leg, the right wing and several major setae. The holotype, with the registration number CASTYPE20352, and the paratype will be deposited in CAS.

Etymology

The species epithet was formed by combining the first three letters of its country of origin with “ovata”, referring to the new species' former affiliation with D. ovata.

Description

[See also section on common characteristics.]

Male. Head. Ground colour yellow to reddish brown depending on the incidence of light, densely silver-white dusted in parts or uniformly (Figs. 7, 8). Holoptic; eyes with few microscopic hairs, facets close to frons clearly enlarged. Frons at midlength almost twice as wide as anterior ocellus, fronto-orbital plates touching throughout the length of the frons, only separated shortly above lunule and directly by the ocellar triangle (Fig. 8), fronto-orbital plate at narrowest part of frons about as wide as anterior ocellus. Parafacial at level of base of antenna about 1.5 times as wide as depth of postpedicel, further downwards almost parallel-sided, slightly wider than anterior ocellus. Facial ridge in lower half about 1.5 times as wide as parafacial. In profile, upper mouth margin in line with profrons and genal depth below lowest eye margin about one third as wide as depth of postpedicel (Fig. 7). When viewed anterodorsally, fronto-orbital plate, parafacial and facial ridge densely silvery-white shiny, only at certain viewing angles fronto-orbital plate dark and parafacial and facial ridge pale yellow, peristomal area and anterior part of gena predominantly yellow to reddish brown (Fig. 7), under certain light conditions densely silver-white dusted, subgena shiny dark brown with some white pollinosity and contrasting with the much lighter anterior part of gena (Fig. 9). Antenna predominantly yellow, under some incidences of light apical half of postpedicel dark yellow, only sparsely dusted (Figs. 7, 8). Postpedicel about 3 times as long as deep and about twice as long as pedicel. Arista in basal third predominantly yellow, apical part yellowish brown, about twice as long as postpedicel, longest hairs of arista at least twice as long as depth of postpedicel. Anterior fourth of fronto-orbital plate with a strong anterior seta at least as long as postpedicel, and a much weaker seta barely half as long as the anterior seta, followed by a much shorter interstitial hair, upper part of frons bare apart from a small reclinate seta-like hair at level of anterior tip of ocellar triangle, not much longer than twice the diameter of the anterior ocellus. Ocellar setae well developed, about 1.5 times as long as anterior fronto-orbital seta. Inner and outer vertical setae not half as long as ocellar seta. Parafacial and facial ridge bare apart from the group of setulae in the lower facial corner. Vibrissal setae strong and about 1.5 times as long as the longest surrounding peristomal setae. Lateral surface of gena reddish brown, weakly dusted and bare, margin of gena with a row of strong dark setae, post-occipital surface more brown and greyish-dusted, with dark seta-like hairs. Proboscis with prementum brown and depending on the incidence of light slightly whitish-dusted or shiny, labella at least twice as long as greatest depth of proboscis; palpus strikingly yellow, clearly somewhat longer than prementum, slender, clavate and slightly flattened.

Thorax. Predominantly yellowish to brownish yellow (Fig. 10). Mesonotum brownish yellow without any dark pattern, depending on viewing angle shiny or partially whitish-dusted; presutural part of mesonotum with a median white-dusted longitudinal stripe tapering toward the transverse suture (Fig. 10). Scutellum purely concolourous with mesonotum, under certain incidences of light more yellow. Pleura yellow, shiny, at certain viewing angles pale yellow, almost whitish in places, somewhat contrasting with the darker mesonotum, partly whitish-dusted when viewed directly anteriorly. Anterior and posterior spiracles yellowish white, posterior spiracle with dark setae at the lower margin. Mesonotum and dorsal lateral surfaces of scutellum covered with rather short and not very strong black setulae, pleura predominantly bare or very sparsely covered with small black hairs. Acrostichals 0+1, more than half as long as the posterior dorsocentral seta; notopleural setae 2, very few short setulae around the anterior and posterior setae; prealar seta shorter than half as long as posterior notopleural seta. Prosternum yellow, with fine hairs along the margin; anepimeron in the upper part with a tuft of dark hairs and a few scattered fine hairs on the lower part; anepisternal setae 1+5 all black and strong, dark interstitial hairs clearly shorter and distinctly weaker than the setae but longer than the ground hairs. Scutellum with basal and preapical setae distinctly shorter than apical and lateral setae but clearly distinguishable, in addition three or four discal setae close to and almost as long as preapical setae, dorsal surface densely covered with dark setulae.

Wing. Stem vein yellow but practically not contrasting with the subsequent predominantly yellowish-brownish vein parts. Radial node and vein R₄₊₅ ventrally with some small setulae. Upper calypter yellowish hyaline, margin distinctly yellowish, lower calypter and margin more whitish yellow. Haltere: stem yellow, knob pale yellow.

Legs. Pulvilli and claws somewhat enlarged, about as long as the corresponding tarsomere. Fore tibia with a short but distinct black median anterodorsal seta. Mid femur in apical half with a complete row of strong dark posteroventral setae not half as long as depth of femur (Fig. 29) and in basal half two posteroventral setae about half as long as depth of femur; no row of distinct anterior bristle-like setae; preapically three strong posterior to posterodorsal setae and one distinct anterodorsal seta. Hind femur in apical half with 3 apical anteroventral setae about as long or longer than the depth of the femur and 0–3 setae at most half as long as the apical ones; a row of dark posteroventral setae about half as long as depth of femur in apical half or two thirds, in basal third 1 or 2 posteroventrals distinctly shorter and weaker; preapically two strong posterodorsal to dorsal setae. Hind tibia without a long posterodorsal seta, in middle third with a strong anterodorsal seta distinctly longer than diameter of tibia and two somewhat shorter anteroventral setae.

Abdomen. Ground colour brownish yellow. Syntergite 1+2 and anterior half of tergite 3 uniformly translucent yellow, posterior half of tergite 3 and the two posterior tergites predominantly brown with a brassy tinge under certain incidences of light (Fig. 10), in almost direct posterior view a poorly defined median yellowish longitudinal stripe on anterior four tergites. Tergites without any significant dusting independent of viewing angle. The brown colouration in the paratype limited mainly to tergites 4 and 5, the median longitudinal stripe more pronounced. Tergites densely covered with small black seta-like hairs, all tergites with rows of marginals, the anterior tergites with mainly short marginals but with a few long ones laterally, tergite 4 with a row of long and strong marginals and with long and strong discals laterally and dorso-laterally, tergite 5 with complete rows of long discals and marginals. Margin of sternite 1 with several dark hairs.

Genitalia. Hypopygium barely perceptible. The male of D. libovata is clearly distinguishable from the other males of this group. Therefore, it was deemed wiser not to extract the genitalia, to avoid inflicting damage on one of the so far only two available specimens of the new species.

Measurements. Length of body 8.4 mm; length of wing 8.9 mm.

Female unknown.]

Remarks and diagnosis

Using EMDEN's key, the specimens run to “D. ovata, var. rutila Stein” due to the body size, the limitation of anteroventral setae to the apical part of the hind femur, and the long discal setae on tergite 5. Dichaetomyia libovata sp. n. is the only species of this group of new species characterized just by one median white longitudinal stripe on the presutural part of the mesonotum, similarly as found on the female syntype of D. ovata. This similarity also leads to the question of whether these two specimens might be the D. ovata males not described so far. Aside from the difference in size, however, both species also differ in several taxonomic characters that cannot only be explained by the specimens belonging to different sexes. Especially since in most Dichaetomyia species sex differences are not very pronounced, apart from the morphology and chaetotaxy of the head.

Dichaetomyia ovata and D. libovata sp. n. can be clearly distinguished by the almost uniformly dark brown subgena and anterior part of gena in D. ovata vs. the dark brown subgena of D. libovata sp. n., which is in striking contrast with the yellowish or reddish anterior part of the gena in the new species (Fig. 9). The mid femur of D. ovata is marked by three or four strong ventral setae in the basal half, a preapical row of about 6 short posteroventral seta-like hairs and by 4 strong preapical posterior to dorsal bristles; in D. libovata sp. n. there are two posteroventral setae in the basal half of the mid femur, a complete row of strong dark posteroventrals in the apical half (Fig. 29), almost half as long as the depth of the femur, and only three posterior to dorsal preapical bristles. The hind femur of D. ovata differs from that of D. libovata sp. n. by a complete but slightly irregular row of six anteroventral setae, three in the basal half and three in the apical third, all about as long as the depth of the femur, and posteroventral surface without any distinct hairs or setae apart from a short row of short hairs preapically; in D. libovata sp. n. there are no long anteroventral setae in the basal half but a complete row of well-developed dark posteroventrals in the apical half to two thirds, the setae about half as long as the depth of the femur.

Material examined

Holotyp e ♀ from Madagascar; marked with three labels with the following inscriptions: 1. CASENT 3009165”, 2. “Madagascar: Mahajanga Province, Parc National de Baie de Baly, 12.4 km 337° NNW Soalala, elev. 10 m 26-30 Nov 2002”, and 3. “16°00′36″S 045°15′54″E coll. Fisher, Griswold et al., California Acad. of Sciences, pitfall trap in tropical dry forest, coll. code: BLF6815”.

Paratypes. 1 ♂ with the registration label “CASENT 3009147” and with the same locality labels as the holotype; 1 ♂ with three labels: 1. The registration number “CASENT 3009707”, 2. “Madagascar: Toliara Prov., Antafoky elev. 55 m, 23°28′43″S 44°3′51″E 25-28 January 2002”, and 3. “Calif. Acad. of Sciences, collectors: Frontier Project, Malaise trap, gallery forest, collection code: MGF003”; 1 ♀ from Madagascar with three labels: 1. The registration number “CASENT 3009178”, 2. The locality label “Toliara Province, Foret Classée d'Analavelona, 29.2 km 343° NNW Mahaboboka, elev. 1100 m, 18-22 Feb 2003”, and 3. “22°40′30″S 044°11′24″E coll. Fisher, Griswold et al. California Acad. of Sciences, pitfall trap, in montane rainforest, code: BLF7817”.

Non-type material: 1 ♀ with the labels 1. “Madagascar: Ankarafantsika (Forest Reserve) near Marovoay, 12-I-1959”, 2. “E. S. ROSS, collector”, and 3. “Dichaetomyia ♀ ovata rutila (St.) det. ZIELKE 1972”. [Specimen glued with right side of thorax on a piece of card; fore tibia and tarsi and mid leg of that side lacking, body otherwise in good condition.]

Remarks. The holotype, with the registration number CASTYPE20353, is in good condition; the paratype CASENT 3009147 will be deposited in CAS, whereas the paratypes CASENT 3009707 and CASENT 3009178 will remain in IBER.

Etymology

The species epithet was formed by combining the first three letters of its region of origin, the Malagasy Region, with “ovata”, referring to the new species' former affiliation with D. ovata.

Description

[See also section on common characteristics.]

Female. Head. Ground colour of upper half mainly dark, lower half somewhat paler, densely dusted greyish-white in parts depending on the incidence of light. Frons almost parallel-sided (Fig. 11), only very slightly dilated towards the anterior margin, distance between eyes at vertex 0.26 times as wide as maximal width of head, at level of anterior ocellus about 3.2 times and at anterior margin of frons about 3.8 times as wide as the distance between the outer margins of the posterior ocelli. Fronto-orbital plate at midlength of frons about two thirds as wide as distance between outer margins of posterior ocelli; frontal vitta slightly oval-shaped, at middle about 3.3 times as wide as fronto-orbital plate at that level, anterior tip of frontal triangle slightly exceeding midlength of frons. Parafacial at level of base of antenna about as broad as depth of postpedicel and at the level where the facial ridge and parafacial separate at most barely half as wide as anterior ocellus. In profile: parafacial not visible (Fig. 12) and genal depth below lowest eye margin about half as wide as depth of postpedicel. In anterodorsal view, frontal vitta and upper half of fronto-orbital plates predominantly dark to blackish, sparsely greyish-dusted, frontal triangle greyish, somewhat shiny and ocellar tubercle dark, lower part of fronto-orbital plates and parafacial whitish grey dusted (Fig. 11), anterior part of gena brownish, only sparsely greyish-dusted, ground colour of face in anterior view greyish, under some viewing angles greyish white dusted; facial ridge greyish white with a strong yellowish brown tinge in upper part, in lower part about as wide as depth of postpedicel. Basal segments of antenna and base of postpedicel until insertion of arista strikingly yellow (Fig. 11), apical part of postpedicel greyish brown or brownish depending on incidence of light, sparsely whitish-dusted. Postpedicel about 3 times as long as broad and about 2.8 times as long as pedicel. Arista yellow only at base, predominantly brownish, about 2.5 times as long as postpedicel, longest hairs of arista at least twice as long as depth of postpedicel. Anterior half of fronto-orbital plate with 2 setae only and 1 or 2 very small interstitial seta-like hairs, the anterior seta about twice as long as the posterior one. An almost complete row of small proclinate setulae between the eye margin and the frontal and orbital setae. Ocellar setae well developed, almost reaching anterior margin of frons, inner vertical seta longer than outer vertical seta but not as long as ocellar seta. Lateral upper surface of gena dark brownish, barely dusted and bare, margin of gena with a row of strong dark setae, post-occipital surface uniformly greyish-dusted and with few short dark seta-like hairs, setae of post-ocellar row well developed. Proboscis fairly short (Fig. 12), prementum pale brownish with a strong yellow tinge in places, predominantly shiny, labella up to 1.5 times as long as greatest depth of proboscis; palpus predominantly brown, apical part under certain light conditions somewhat paler (Fig. 12), slender, weakly clavate and at most marginally longer than prementum.

Thorax. Basic colour predominantly yellowish. In dorsal view, mesonotum yellow, only weakly shiny, under certain conditions of light with a brownish grey tinge in some places, shifting with changing light conditions; presutural part of mesonotum with a broad median whitish grey longitudinal stripe (Fig. 14), somewhat shiny, tapering towards the transverse suture and continued in the postsutural part as a stripe half as wide and almost reaching the scutellar suture. Outside and along each of the rows of presutural dorsocentral setae another whitish grey longitudinal stripe, not as wide as the median stripe, strongly tapering to the transverse suture and extending in the postsutural part as a very narrow stripe barely reaching the median dorsocentral seta. Postpronotum and notopleuron translucent whitish, somewhat contrasting with the yellow mesonotum. Scutellum about the same colour as mesonotum, in general less brownish. Pleura pale yellow, slightly shiny, under certain light conditions intersegmental membranes strikingly white (Fig. 15); when viewed directly anteriorly, weakly whitish-dusted in places. Anterior and posterior spiracles purely white. Mesonotum and scutellum covered with rather short black strong setulae, pleura predominantly bare or very sparsely covered with short fine black hairs. Notopleuron with very few short and fine setulae; prealar seta somewhat shorter than posterior notopleural seta; prosternum yellow, with several hair-like setae; anepimeron in upper part with a tuft of dark hairs and a few scattered fine hairs in lower part; anepisternal setae 1+6, all black and strong, dark interstitial hairs much weaker, most barely one third as long as the long setae. Scutellum with basal and preapical setae distinctly shorter than apical and lateral setae but stronger and clearly distinguishable from hairs on the scutellum.

Wing. Membrane with a brownish tinge (Fig. 15); veins including basal parts yellowish brown, costal spine almost three times as long as adjacent bristles but not very pronounced. Upper calypter almost hyaline, margin with a narrow dark brown seam (Fig. 15), lower calypter whitish hyaline, margin broad and white. Stem and knob of haltere whitish, at most with a very weak yellowish tinge under certain viewing angles.

Legs. Coxae, trochanters, femora and tibiae yellow, tarsi somewhat darker yellow (Fig. 15). Fore tibia without anterodorsal setae. Mid femur without any long hairs or setae (Fig. 27), only at base with a posteroventral hair slightly longer than half the depth of the femur, and with one anteroventral row and one posteroventral row of short setae in apical third, setae not as long as half the depth of the femur, preapically with 3 posterior to almost dorsal setae and one distinct anterodorsal seta. Hind femur in apical third with 2 anteroventral setae slightly longer than depth of femur, a third distinctly shorter seta basad to the 2 others may be present (Fig. 27), a short row of posteroventral seta-like hairs about one third as long as depth of femur in apical fourth, preapically 2 strong posterodorsal to dorsal setae. Hind tibia with a median anterodorsal seta slightly longer than diameter of tibia and a shorter anteroventral seta barely as long as diameter of tibia and without any other posterodorsal seta apart from the apical seta.

Abdomen. Ground colour yellow, mainly in front half of tergites faint brownish grey transverse bands shifting under changing light conditions (Fig. 14), front part of syntergite 1+2 translucent glossy white. Tergites densely covered with small black setulae, all tergites with a complete row of marginal setae, usually rather short dorsocentrally and distinctly longer laterally, with the exception of tergite 5 with longer marginals and a few distinct discal setae. Lateral margin of sternite 1 with a few strikingly small dark setulae in clear contrast with the seta-like hairs of the subsequent sternites.

Genitalia not investigated.

Measurements. Body length 5.5–6.0 mm, wing length 5.5 mm.

Male. Head. Ground colour brown to dark brown. Holoptic; eyes with very few microscopic hairs, facets close to frons clearly enlarged. Frons at midlength barely as wide as diameter of anterior ocellus (Fig. 16), fronto-orbital plates touching throughout the length of the frons, only separated shortly above lunule and directly in front of anterior tip of ocellar tubercle. Fronto-orbital plate at narrowest part of frons about one third as wide as anterior ocellus. Parafacial at level of base of antenna as wide as anterior ocellus and practically parallel-sided further downwards throughout its length. Facial ridge in lower half almost as wide as depth of postpedicel. In profile, upper mouth margin in line with profrons; parafacial somewhat visible throughout its length; genal depth below lowest eye margin about as wide as depth of postpedicel (Fig. 17). In anterodorsal view, upper third of fronto-orbital plate dark, the anterior two thirds and parafacial densely white-dusted, under certain viewing angles these parts darker and sparsely greyish-dusted; facial ridge whitish except for base with a more or less distinct brownish tinge independent of the incidence of light. Antenna with all segments yellow, pedicel an intense yellow, postpedicel pale yellow, under certain qualities of light somewhat whitish-dusted. Postpedicel almost 4 times as long as deep and about 3 times as long as pedicel. Arista predominantly brownish, only in basal third somewhat yellowish, about twice as long as postpedicel, longest hairs of arista at least 2.5 times as long as depth of postpedicel. Anterior fifth of fronto-orbital plate with one stronger anterior seta almost as long as postpedicel and another subsequent seta about half as long as the anterior seta, followed by a much shorter interstitial hair, upper part of frons bare apart from a small reclinate seta-like hair at level of anterior tip of ocellar triangle, not much longer than twice the diameter of the anterior ocellus, and an even smaller reclinate setula shortly below. Ocellar setae well developed, about 1.5 times as long as anterior fronto-orbital seta, inner vertical seta somewhat shorter than outer vertical seta, both distinctly shorter than ocellar setae. Parafacial and facial ridge bare apart from the group of setulae in the facial corner adjacent to the peristomal area. Vibrissal setae distinctly stronger, but not much longer than the longest surrounding peristomal setae. Lateral surface of gena brown to brownish grey, sparsely dusted under certain incidences of light, surface directly below lower eye margin bare, lower margin with strong dark setae, post-occipital surface brownish and densely greyish-dusted, with dark short setae. Proboscis with prementum shiny brown, a weak yellow shine under certain viewing angles, labella about 1.5 times as long as greatest depth of proboscis; palpus brown (Fig. 17), under certain viewing angles apical part with a yellowish tinge, somewhat clavate and about as long as prementum.

Thorax. Very similar to that of female. Ground colour yellow, the brownish grey tinge in more or less shifting places more intense. The longitudinal stripes more distinct in posterodorsal view, the paramedian stripes not as long as in female and in their posterior part less clearly demarcated. In dorsal view a very thin brown line, partly very faint, connecting the bases of the dorsocentral setae. Pleura more intense yellow than in females, the white intersegmental membranes more strongly contrasting under certain light conditions. Chaetotaxy similar to that of female, but prealar seta much shorter than posterior notopleural seta; posterior strong long intra-alar seta not detectable; prosternum with rather short fine dark hairs; scutellum with less strong basal and preapical setae, not clearly distinguishable from longer hairs on disc of scutellum.

Wing predominantly as in female. Only one of the four examined wings with 2 setulae on the basal ventral part of vein R₄₊₅, all others bare. Margin of lower calypter with a yellow tinge under certain viewing angles.

Legs. Similar to legs of female (for example mid femur, Fig. 28), but pulvilli and claws almost half as long as the corresponding tarsomere. [Fore femora missing.] Hind femur with one median posteroventral seta-like hair, somewhat shorter than depth of femur, some of the setae of the apical posteroventral row about as long as depth of femur. One of the four examined hind tibiae of the two males with an additional short anteroventral seta.

Abdomen. Ground colour in general as in female, the yellow colour more intense and slightly more shiny. The marginals of tergites 4 and 5 somewhat stronger than in female.

Genitalia. Like all sternites, sternite 5 also pale yellow; hypopygium light yellow and not prominent.

Measurements. Body length 6.5 mm, wing length 6.0 mm.

Remarks and diagnosis

The males and females of this new species were originally identified and listed by Couri et al. as D. ovata. Apparently, the male characteristics of D. ovata mentioned in CourI et al.'s identification key are based on these specimens, which turned out to contradict the characteristics of the female syntype, triggering this comparative investigation. Of the specimens studied here, those belonging to Dichaetomyia malovata sp. n. are certainly those least similar to D. ovata. In Emden's key, however, they key out as D. ovata var. rutila. When compared to the 10 mm large female syntype of D. ovata, the small body size (5.5–6.5 mm) of the five specimens of D. malovata sp. n. is immediately noticeable. In addition, the specimens of the new species are not very shiny and mostly pale yellow in colour, with a more or less strong whitish tinge depending on the lighting. The whole body of D. ovata, on the other hand, appears glossy and is predominantly yellow to brownish yellow in colour. Other distinguishing features are the almost uniformly brown palpi of D. malovata sp. n. (Figs. 12, 17), the three white elongated spots or stripes on the anterior mesonotum (Fig. 14), extending up to the second postsutural dorsocentral seta under certain light conditions, and the very thin brown line between the setae of the dorsocentral row in some specimens, particularly the males. In D. ovata the palpi are strikingly yellow (Fig. 2), there is only one median elongated white spot on the mesonotum (Fig. 3), which under certain viewing angles may extend to the transverse suture, and there is no brown line between the dorsocentral setae. The calypters of D. malovata sp. n. are predominantly matt whitish hyaline and the margin of the upper calypter is marked by a narrow dark brown seam (Fig. 15), whereas the calypters of D. ovata are transparent yellowish and the margin of the upper calypter is, as in all other species of this group, without a dark frame. While the abdomen of D. malovata sp. n. is marked in addition to the yellow colouration also by shifting, slightly brownish grey band-like areas (Fig. 14) depending on the incidence of light, the abdomen of D. ovata is predominantly brownish in colour (Fig. 5). The chaetotaxy of the legs also differs significantly in the females of both species. Whereas D. malovata sp. n. has no median setae on the fore tibia and no distinct setae on the mid femur (Fig. 27) apart from three preapical posterior to dorsal bristles, D. ovata is characterized by a short but distinct anterodorsal seta in the distal half of fore tibia, by ventral and anterior setae in the basal half of the mid femur (Fig. 26) and by four strong apical posterior to dorsal bristles. The hind femur of D. malovata sp. n. has only two strong anteroventral setae in the apical third (Fig. 27) and one anterodorsal and one anteroventral seta at the middle third of the hind tibia, while D. ovata has an irregular row of anteroventrals throughout the length of the femur (Fig. 26) and the hind tibia has one anterodorsal and two anteroventral setae.

Males of the five species treated herein are known only for D. libovata sp. n. and D. malovata sp. n. They differ in several features. The palpi of D. libovata sp. n. are purely yellow (Fig. 7), the subgena is dark brown and the anterior part of the gena is of a contrasting yellow to brownish yellow (Fig. 9), while in D. malovata sp. n. the palpi are predominantly brownish (Fig. 17) and the subgena and anterior part of the gena are almost uniformly brown. The presutural part of the mesonotum of D. libovata sp. n. has only one median longitudinal white stripe (Fig. 10), and there is no brown line between the setae of the dorsocentral row; whereas D. malovata sp. n. is characterized by a broad median and two narrow paramedian longitudinal white stripes depending on the incidence of light, the stripes extend up to the middle of the postsutural part of the mesonotum, and in addition each row of dorsocentral setae is marked by a more or less distinct brown line between the setae. At least the last two tergites of the abdomen of D. libovata sp. n. are predominantly dark brownish (Fig. 10), while in D. malovata sp. n. they are predominantly yellow to greyish yellow. The hind femur of D. libovata sp. n. is marked in the apical half or two thirds by a row of dark posteroventral setae almost as long as the depth of the femur, and in the basal third by one or two distinctly shorter and weaker posteroventrals; the hind femur of D. malovata sp. n. has only one median posteroventral seta-like hair, somewhat shorter than the depth of the femur, and in apical fourth a short row of posteroventral seta-like hairs, some of which are as long as the depth of the femur.

Type material

Holotype ♀ from Nigeria; the locality label bears the inscription “Nigeria, Kabba, II.20.1949, B. Malkin”, and an identification label reads “Dichaetomyia ovata rutila St. det. E. ZIELKE 1972”.

Remarks. The holotype lacks the left mid and hind legs and the tarsi of the left fore leg, but is otherwise in good condition. It will be deposited in CAS with the registration number CASTYPE20354.

Etymology

The species epithet is formed by combining the first two letters of its country of origin with “ovata”, referring to the new species' former affiliation with D. ovata.

Description

[See also section on common characteristics.]

Female. Head. Ground colour of frons mainly dark, lower parts of head yellow to brownish yellow, some parts densely silvery-white dusted depending on the incidence of light (Fig. 19). Frons dilated towards anterior margin, distance between eyes at vertex 0.27 times as wide as maximal width of head, at level of anterior ocellus about 3.2 times and at anterior margin of frons 4.1 times as wide as distance between outer margins of posterior ocelli. Fronto-orbital plate at midlength of frons about two thirds as wide as distance between outer margins of posterior ocelli; depending on viewing angle, frontal vitta practically subparallel or slightly oval, at middle about 3 times as wide as width of fronto-orbital plate, frontal triangle poorly demarcated, either reaching anterior margin or midlength of frons depending on incidence of light. Parafacial at level of base of antenna almost as wide as depth of postpedicel and at the lower end about as wide as anterior ocellus. Facial ridge in lower half about twice as wide as parafacial. In profile, parafacial visible throughout the entire length; genal depth below lowest eye margin about half as wide as depth of postpedicel (Fig. 18). When viewed anteriorly, fronto-orbital plates dark and in lower half predominantly greyish-dusted, frontal vitta contrasting dark, in lower third reddish brown, partly dusted depending on viewing angle, frontal triangle and ocellar tubercle dark, under some viewing angles somewhat greyish-dusted. Parafacial and facial ridge pale yellow or densely silver-white or whitish dusted depending on incidence of light; anterior part of gena predominantly yellow, partly with a brownish tinge, under certain conditions of light densely silvery-white dusted, ground colour of face pale yellow, under some viewing angles densely white-dusted. Basal segments of antenna and basal half of postpedicel strikingly yellow, distal half more or less darkened depending on light conditions (Fig. 18), only sparsely dusted. Postpedicel about 3.2 times as long as deep and about 2.8 times as long as pedicel. Arista about twice as long as postpedicel, longest hairs of arista almost twice as long as depth of postpedicel. Anterior half of fronto-orbital plate with a strikingly strong anterior seta almost as long as the length of the arista, followed by 3 inclinate seta-like hairs much shorter than the anterior seta, only about half the length of the longest arista hairs; between the eye margin and the frontal and orbital setae some small proclinate setulae. Vibrissal setae strong and about 3 times as long as the longest surrounding peristomal setae. Lateral surface of gena sparsely dusted and bare, yellowish brown and practically in no clear contrast with the somewhat browner subgena, which also has a yellowish tinge under certain light conditions, margin of gena with a row of strong dark setae, post-occipital surface more brown and greyish-dusted, only sparsely covered with dark seta-like hairs. Proboscis short and strong, prementum brown and slightly whitish-dusted or shiny depending on incidence of light, labella at least twice as long as greatest depth of proboscis; palpus strikingly yellow (Fig. 18), slightly clavate and flattened, about 1.5 times as long as prementum.

Thorax. Predominantly yellowish to brownish yellow. Mesonotum yellow with a brownish tinge, without a dark pattern, shiny or partially whitish-dusted depending on viewing angle; presutural part of mesonotum with a median white-dusted patch and a white paramedian patch on each side between the anterior presutural dorsocentral seta and the posthumeral seta (Fig. 20), when viewed postero-dorsally the patches appear as white stripes tapering toward the transverse suture. Scutellum of about the same colour as mesonotum. Pleura of a shiny pure yellow or even pale yellow, somewhat contrasting with the somewhat darker mesonotum, when viewed directly anteriorly, partly whitish-dusted. Anterior and posterior spiracles pale yellow. Mesonotum and dorsal lateral surfaces of scutellum covered with rather short black setulae, pleura predominantly bare or with a few small black hairs. Notopleuron with a few fine setulae around the anterior and posterior seta; prealar seta slightly shorter than posterior notopleural seta; prosternum with a few black hair-like setae; upper part of anepimeron with a tuft of dark hairs and a few fine hairs on the posterior surface, the hairs about as long as the hairs of the tuft (Fig. 21); anepisternal setae 1+5, all black and strong, dark interstitial hairs much weaker and at most a quarter as long as the setae. Scutellum with basal and preapical setae distinctly shorter than apical and lateral setae, but clearly distinguishable from the ground hairs.

Wing. Stem vein yellow, not strongly contrasting with the subsequent brownish yellow parts of the veins. Upper calypter shiny yellowish hyaline, margin yellowish, lower calypter matt whitish and margin more whitish. Stem of haltere pale yellow, knob yellow.

Legs. Fore tibia with a short but very distinct black median anterodorsal seta. Mid femur with a complete row of dark ventral to anteroventral setae about one third as long as depth of femur, in basal half a row of short anterior bristle-like setae; in apical third a row of posteroventral setae about half as long as depth of femur, preapically with 3 strong posterior to posterodorsal setae and a distinct anterodorsal seta. Hind femur in apical third with 3 or 4 anteroventrals, some of which are slightly longer than the depth of the femur, in basal third 2 anteroventral setae, one strong and long, the more basad one distinctly shorter, in addition 1 distinct seta-like posteroventral hair somewhat longer than depth of femur, in middle third 2 strong and long posteroventral setae about as long as depth of femur, apical two fifths with a row of dark posteroventral setae about half as long as depth of femur, preapically 2 strong posterodorsal to dorsal setae. Hind tibia without a posterodorsal seta, in middle third with an anterodorsal seta slightly longer than diameter of tibia and 2 weaker and shorter anteroventral setae barely as long as diameter of tibia.

Abdomen. Syntergite 1+2 and tergite 3 uniformly translucent yellow, the two posterior tergites yellowish brownish, appearing clearly darker than the thorax, without any significant dusting independent of the viewing angle. Tergites densely covered with small black setulae, syntergite 1+2 and tergite 3 with a few longer marginals laterally, tergites 4 and 5 with a row of stronger marginals, both tergites additionally with a few discal setae laterally, but no complete row of discal setae detectable. Margin of sternite 1 densely covered with several dark setulae.

Genitalia not investigated.

Measurements. Body length 8.6 mm; wing length 8.0 mm.

Male unknown.]

Remarks and diagnosis

Using EMDEN's identification key, the female holotype of D. niovata sp. n. was originally identified as D. ovata rutila due to its body size and morphological characteristics. However, D. niovata sp. n. is characterized on the anterior mesonotum by three oblong white-dusted patches (Fig. 20) extending up to the transverse suture under certain light conditions, whereas D. ovata has only the median white marking on the anterior part of the mesonotum (Fig. 3). The mid femur of D. niovata sp. n. has a complete row of dark ventral setae about one third as long as the depth of the femur and preapically three strong posterior to posterodorsal bristles; D. ovata has in the basal half of the mid femur only three or four ventral setae almost half as long as the depth of the femur, and four apical posterior to dorsal bristles. The hind femur of D. niovata sp. n. is marked in its apical two fifths with a row of dark posteroventral setae about half as long as the depth of the femur, whereas such a row is lacking in D. ovata.

The new species can be distinguished from D. malovata sp. n., another new species with three white longitudinal markings on the mesonotum, by the larger body size (more than 8 mm) and the shiny yellow body colour with distinctly brownish parts of the abdomen (Fig. 20), whereas D. malovata sp. n. is clearly smaller (about 6 mm) and the body is pale yellow with a whitish tinge in parts, more matt than shiny, and without large brown areas (Fig. 1). In addition, the palpi are completely yellow (Fig. 18), the parafacial is well visible in profile and only a few proclinate setulae are present between the eye margin and frontal and orbital setae in D. niovata sp. n., whereas the palpi are predominantly brownish, the parafacial is not visible in profile (Fig. 12) and there is an almost complete row of small proclinate setulae between the eye margin and the frontal and orbital setae in females of D. malovata sp. n. The margin of the upper calypter of D. malovata sp. n. is marked by a dark seam (Fig. 13), which is absent in D. niovata sp. n. The latter is also characterized by fore tibia with a short but very distinct black median anterodorsal seta and by mid femur with a complete row of dark ventral setae about one third as long as the depth of the femur, in addition to a row of short anterior bristle-like setae in the basal half; the fore tibia and mid femur of D. malovata sp. n. are without such setae. The hind femur of D. niovata has in its basal third at least one long anteroventral seta and one distinct seta-like posteroventral hair somewhat longer than the depth of the femur, and in the middle third two strong and long posteroventral setae about as long as the depth of the femur, these setae also not present in D. malovata sp. n. The lateral parts of the margin of sternite 1 of the latter species bear only a few strikingly small dark setulae; the margin of sternite 1 of D. niovata sp. n. is broadly and fairly densely covered with numerous hair-like setae throughout the length of the margin.

Type material

Holotype ♀ from Tanzania (SMNS), carrying four small labels bearing the following inscriptions: 1. “Torina 4.-18.III.1952, D. O. Afrika Exp.”; 2. “Torina 15.III.52” [handwritten]; 3. “Dichaetomyia ovata (St.) det. Paterson 53; 4. “SMNS_ Dip_007136”.

Remarks. Neither PATERSON's (1956) publication nor the location labels attached to the fly revealed in which East African country the fly was found. A reference to “Torina” in the Serengeti, Tanzania was found on the Internet, and HANS-PETER TSCHORSNIG (SMNS) kindly confirmed that this is indeed the name of a creek in the Serengeti, on the banks of which ERWIN LINDNER (formerly SMNS) collected various insects. Apart from a small tear in the basal part of the anterior margin of each wing, the holotype is in excellent condition. It will be returned and deposited in SMNS with the registration number SMNS_ Dip_007136, provided by the museum.

Etymology

The species epithet was formed by combining the first three letters of its country of origin with “ovata”, referring to the new species' former affiliation with D. ovata.

Description

[See also section on common characteristics.]

Female.Head.Groundcolourinupperhalfabovelunule almostblack,lowerhalfstrikinglypaler,varyingfromlight yellow to yellowish brown, or under certain incidences of light densely silvery-white dusted (Fig. 23). Frons almost parallel-sided, only slightly dilated towards the anterior margin, distance between eyes at vertex 0.31 times as wide as maximal width of head, at level of anterior ocellus about 4.0 times and at anterior margin of frons about 4.8 times as wide as distance between outer margins of posterior ocelli. Fronto-orbital plate at midlength of frons about two thirds as wide as distance between outer margins of posterior ocelli; frontal vitta slightly oval-shaped, at middle about 4 times as wide as fronto-orbital plate, frontal triangle somewhat shiny, in anterior view reaching at least midlength of frons, the anterior tip extended as a dark-greyish line almost reaching the anterior margin. Parafacial at level of base of antenna about 1.5 times as wide as postpedicel and at the lower end almost twice as broad as anterior ocellus. In profile, parafacial clearly visible throughout its length; genal depth below lowest eye margin almost as broad as depth of postpedicel (Fig. 22). Facial ridge in lower half about as wide as depth of postpedicel. In anterior view fronto-orbital plates predominantly brown anteriorly and dark brown in upper part, with a few small patches of silvery-white dusting, frontal vitta dark and uniformly sparsely greyish-white dusted, frontal triangle more densely dusted than frontal vitta, ocellar tubercle dark. Ground colour of parafacial and face light yellow, anterior part of gena brownish yellow, in anterior view all parts predominantly white-dusted, some yellow spots visible depending on viewing angle. All segments of antenna strikingly yellow, apical third of postpedicel with a brownish tinge under certain viewing angles (Figs. 22, 23). Postpedicel at least 3 times as long as deep and about twice as long as pedicel. Arista about 2.5 times as long as postpedicel, longest hairs of arista almost twice as long as depth of postpedicel. Anterior half of fronto-orbital plate with 4 setae, the anterior seta very strong, the next one less than half as long and the uppermost ones distinctly shorter and weaker, no small setae at midlength, the lower orbital seta slightly below and less than half as long as the upper seta. Only about three small proclinate setulae near anterior frontal seta and one or two near orbital setae, surface of fronto-orbital plate otherwise bare. Vibrissal seta strong and about 1.5 times as long as the longest surrounding peristomal setae. Anterior and lateral surfaces of gena brown, weakly dusted and bare, not contrasting with the brown, slightly dusted subgena, margin of gena with a row of strong dark setae; post-occipital surface greyish-dusted and only sparsely covered with dark, predominantly short setulae. Proboscis not slender, prementum brown and slightly whitish-dusted or somewhat shiny depending on incidence of light, labella about twice as long as greatest depth of proboscis; palpus yellow, slender, weakly clavate and clearly longer than prementum (Fig. 22).

Thorax. Predominantly yellowish. Mesonotum shiny yellow with a brownish tinge under certain viewing angles, in anterior view partially whitish-dusted. In dorsal view presutural part of mesonotum with a white dusted median stripe, when viewed posteriorly, tapering toward and reaching the transverse suture, with two white dusted paramedian oblong patches between the anterior presutural dorsocentral seta and the posthumeral seta, not strongly developed in dorsal view (Fig. 24), in posterior view the patches tapering to a distinct white stripe along the presutural dorsocentrals, almost reaching the transverse suture, additionally with a very narrow brownish line not much broader than the bases of the dorsocentral setae and extending along the row of dorsocentrals (Fig. 24). Scutellum of about the same colour as mesonotum. Pleura shiny pale yellow, somewhat contrasting with the darker yellow mesonotum, when viewed directly anteriorly, partly whitish-dusted. Anterior and posterior spiracles pale yellow. Mesonotum and dorso-lateral surfaces of scutellum covered with rather short black setulae, pleura predominantly bare or with strikingly short setula-like fine hairs. Acrostichals 0+1, more than half as long as the posterior dorsocentral seta; notopleuron with several tiny setulae close to the posterior seta, the setulae significantly smaller than those of the neighbouring pleura; prealar seta slightly shorter than posterior notopleural seta. Prosternum yellow with some yellow hairs difficult to see due to the lack of contrast with the surroundings; upper part of anepimeron with a tuft of dark hairs, the hairs below it are scattered and resemble strikingly small setulae (Fig. 25) or are at most very fine, short hairs; anepisternal setae 1+6 all black and strong but of different lengths, interstitial hairs fairly short. Scutellum with basal setae strongly developed, but not as strong as the two longer pairs of apical and lateral setae, preapical setae clearly weaker but distinct. In addition, a pair of discal setae about as strong as the preapical seta laterad to each preapical seta.

Wing. Membrane with a strong brownish tinge (Fig. 24), stem vein yellowish, subsequent parts of veins brown. Both calypters transparent yellow, margins yellowish to yellow. Stem and knob of haltere yellow.

Legs. Fore tibia without a distinct median anterodorsal seta. Mid femur only with an irregular row of posteroventrals about one third as long as depth of femur, preapically with a row of short but strong posteroventral setae and 3 distinct posterior to almost dorsal setae about as long as depth of femur and a shorter anterodorsal seta. Hind femur in apical third with a row of anteroventral setae, the 3 most apical setae about as long as depth of femur, the others shorter (Fig. 30), in apical fourth or fifth a short row of short but strong posteroventral setae almost as long as depth of femur, preapically two strong posterodorsal to dorsal setae. Hind tibia without a posterodorsal seta, in distal half with anterodorsal seta slightly longer than diameter of tibia and one shorter anteroventral seta barely as long as diameter of tibia, the right tibia with a second anteroventral seta rather close to and barely half as long as the slightly distal seta.

Abdomen. Apart from the more yellowish anterior part of syntergite 1+2, posterior part of abdomen uniformly predominantly brownish with a yellowish tinge, distinctly darker than the thorax (Fig. 24). Tergites densely covered with small black setulae, anterior tergites with distinct but not very long lateral marginal setae, tergite 4 with a row of distinct marginals, the dorsal median ones clearly shorter, tergite 5 with a row of marginals in addition to an incomplete row of discal setae, the dorsal median setae lacking. Margin of sternite 1 with short yellowish hairs.

Genitalia not investigated.

Measurements. Body length 10.7 mm; wing length 10.5 mm.

Male unknown.]

Remarks and diagnosis

The female holotype and a male from the same locality in Tanzania were originally identified as D. ovata and listed with other muscid species from East Africa by PATERSON (1956), mentioning that the specimens were about 10 mm long and that the female had “4–5 distinct setae at the apex of the anteroventral surface, while the male has 7 of these setae distinct on the apical half”. However, Paterson did not elaborate on this difference compared to the description of D. ovata. In order to include an identified male of D. ovata in the investigations, SMNS was asked to provide the two specimens for comparative investigations; like the syntype of D. ovata, the two specimens originated from East Africa. Unfortunately, the male was not found in the SMNS collection and its whereabouts are unknown, but the female was loaned to IBER. The specimen was even somewhat larger than the female syntype of D. ovata and, accordingly, significantly larger than all other so-called “D. ovata” specimens included in this study. In a direct comparison with the female syntype of D. ovata, however, it turned out that the specimen from Tanzania differed from D. ovata not only by a different chaetotaxy of the hind femur, but also by three white-dusted elongated spots on the anterior mesonotum, and not just one median stripe like the syntype of D. ovata. Obviously, it was a representative of a hitherto unknown species, described above as Dichaetomyia tanovata sp. n. The new species is characterized by the ground colour of the lower half of the head varying from light yellow to yellowish brown, by the distance between the eyes at the vertex being almost one third (0.31 times) as wide as the maximum width of the head, and by all segments of the antenna strikingly yellow (Fig. 22); the apical third of the postpedicel, however, shows a slight brownish tinge under certain incidences of light. In D. ovata, the ground colour of the head is mainly dark brown, the distance between the eyes at the vertex is about a quarter (0.27 times) as wide as the maximal width of the head, and only the basal segments of the antenna and the base of the postpedicel until the insertion of the arista are strikingly yellow, the remaining part of postpedicel being dark brown and greyish-dusted (Fig. 2). The prosternum of D. tanovata sp. n. bears some yellow hairs, which are difficult to detect due to the prosternum being yellow as well; the hairs below the very dark tuft of hairs on the upper part of the anepimeron consist of scattered, conspicuously small setulae (Fig. 25) or at most very fine, short hairs; the also yellow prosternum of D. ovata has dark hair-like setae, and the hairs below the tuft of strong dark hairs on the anepimeron are about as long as or longer than the hairs constituting the tuft (Fig. 6). The fore tibia of D. ovata is marked by a distinct black short median anterodorsal seta, which is lacking in D. tanovata sp. n. The basal half of the mid femur of D. ovata has a row of about four dark ventral setae about one third as long as the depth of the femur and a row of short but distinct anterior bristle-like setae (Fig. 26), and preapically a short row of about six short posteroventral seta-like hairs and four strong posterior to almost dorsal bristles; in D. tanovata sp. n. the mid femur lacks a row of distinct anterior setae but has a complete irregular row of posteroventrals about one third as long as the depth of the femur, the preapical posteroventrals of the row are fairly strong setae and there are only three preapical posterior to almost dorsal bristles. The hind femur of D. ovata differs from the hind femur of D. tanovata sp. n. by having, in the basal half, two anteroventral and two posteroventral setae and a median anteroventral seta in addition, all setae being almost as long as the depth of the femur (Fig. 26), whereas there are no long setae in the basal half of the hind femur of D. tanovata sp. n. (Fig. 30); however, the new species is marked preapically by a row of strong posteroventral setae almost as long as the depth of the femur, whereas these posteroventrals are hair-like, much shorter and weaker, in D. ovata. The hind tibia of D. ovata has two anteroventrals, whereas it has only one anteroventral seta in D. tanovata sp. n. The margin of sternite 1 of D. tanovata sp. n. has several blackish setulae, whereas in D. ovata not only the margin but also the surface anterior to the margin of sternite 1 are covered with dark setulae.

Compared to two of the other new species described herein, D. nigovata sp. n. and D. malovata sp. n., both of which also have three white markings on the presutural mesonotum, D. tanovata sp. n. is significantly closer to D. niovata sp. n. These two species can be distinguished not only by the size of the body (10.7 mm vs. 8.6 mm), but also by the distance between the eyes at the vertex, almost one third as wide as the maximal width of the head in D. tanovata sp. n. and slightly more than one quarter in D. niovata sp. n. The vibrissal seta of D. tanovata sp. n. is about 1.5 times as long as the longest peristomal seta, whereas in D. niovata sp. n. the vibrissal seta is three times as long. The prosternum of D. tanovata sp. n. is marked by yellow hairs and the hairs below the tuft of strong dark hairs on the anepimeron are strikingly small setulae or at most very fine, short hairs, whereas in D. niovata sp. n. the hairs on the prosternum are black and more seta-like, and the fairly few hairs below the tuft of strong dark hairs on the anepimeron are stronger and at least more than half as long as the hairs of the tuft (Fig. 21). The fore tibia of D. niovata sp. n. is marked by a distinct black short median anterodorsal seta, the hind femur in basal third by two anteroventral setae, one strong and long, the more basad one distinctly shorter, by one distinct seta-like posteroventral hair somewhat longer than the depth of the femur, and in middle third by two strong and long posteroventral setae about as long as the depth of the femur; all these setae are absent in D. tanovata sp. n. The abdomen of the latter species is predominantly brownish with a yellowish tinge, distinctly darker than the thorax, whereas the anterior abdominal segments of D. niovata sp. n. are uniformly translucent yellow and only the two posterior tergites are yellowish brown in parts.