A new species from Uganda, Caenis longilobata sp. n., is described on the basis of adult males. Melanic specimens of Caenis are recorded from Uganda and tentatively assigned to Caenis jinjana Kimmins, 1956, a widespread African species already known from the country, and its description is amended.
Aus Uganda wird die neue Art Caenis longilobata sp. n. anhand von Männchen beschrieben. Melanistische Exemplare von Caenis aus Uganda werden der bereits aus Uganda bekannten Caenis jinjana Kimmins, 1956 zugeordnet, deren ursprüngliche Beschreibung ergänzt wird.
Introduction
Seven species of Caenidae had previously been recorded from Uganda, listed here in the order of their first description. Caenis cibaria (Eaton, 1879) was first described from Lake Malawi and named (from the Latin ‘cibaria’ = related to food) after the local tradition of pressing them into cakes together with other water insects (Eaton 1879); later, the species was also found in Uganda (Mengo-Entebbe). Kimmins (1939) described Caenis edwardsi Kimmins, 1939 from the Ruwenzori mountains, and later Caenis brevipes Kimmins, 1956 and C. jinjana Kimmins, 1956. The latter two species are widely distributed in Africa: C. brevipes in Ethiopia, Gambia, Kenya, Senegal, Sudan, Tanzania (Malzacher 1993); Guinea, Ivory Coast, Mali (Malzacher 2011); South Africa (Malzacher 2012), and C. jinjana in Ethiopia, Senegal (Malzacher 1993); Togo, Guinea, Ivory Coast, Mali (Malzacher 2011); South Africa (Malzacher 2012); Kenya, (Malzacher 2022b); Angola (DE Moor et al. 2000; Malzacher & Barber-James 2021). Afrocaenis major was first described as Caenopsella major by Gillies (1977), who later transferred it to the new genus Afrocaenis (Gillies 1982). Finally, Malzacher (1987, 1990) described Afrocercus forcipatus and Caenis corbeti, respectively, from the collection of the Natural History Museum, London.
Here, a new species is described from Uganda, increasing the Caenidae fauna of the country to eight species.
Material and methods
The material investigated was collected by WOLFRAM GRAF (Vienna). Specimens were examined with a Wild M3 binocular microscope, whereas line drawings were made with the aid of a Zeiss camera lucida attached to a Leitz Laborlux microscope; drawings were digitised in Photo Filtre v. 6.5.2. Specimens were photographed in series with different focal planes through a Leica Z16 APO Macroscope equipped with a Leica DFC450 Digital Camera using Leica Application Suite v. 3.1.8. Resulting photo stacks were processed with Helicon Focus Pro to obtain combined photographs with extended depth of field. The material is stored at the State Museum of Natural History in Stuttgart, Germany (SMNS) in 75% ethanol, after initial preservation in formalin.
Systematic account
Caenis longilobata sp. n.
(Figs. 1–3)
Type material
Holotype ♂ (imago on microslide), SMNS_EPH_011996_M: Western Uganda, Kabarole district, Kalitutsi Lodge, 0.663375N 30.267559E, 1525 m, 21.09.2022, leg. W. GRAF.
Paratypes. 3 ♂♂, imagines, SMNS_EPH_011997_A. Same collecting data as holotype.
Etymology
The species epithet refers to the very long penis lobes.
Description (male imago)
Measurements, ratios and colouration. Body length: 4.5–5.0 mm; wing length: 4.0–4.5 mm; length of foreleg: 3.0–3.5; cercus: 13 mm; terminal filament: 15 mm. Ratio of forefemur: foretibia = 0.54–0.59; ratio of foretibia: foretarsus = 1.67–1.72; ratio of foreleg: hind leg = 1.50–1.62; ratio of 1st: 2nd: 3rd: 4th: 5th segments of foretarsus = 1: 2.7–3.5: 1.4–1.6: 1.2–1.5: 1.3–1.5.
Colouration of cuticle (Fig. 1): Meso- and metanotum, pleura, parts of prosternum, all coxae and forefemora of different intensities of brown; wide band along median notal suture clearly lighter. Other parts yellowish to white. Epidermal pigmentation: Head and pronotum intense blackish brown to black. Scutellum moderately pigmented. Abdominal terga greyish brown to blackish brown (posterior segments), medially lighter; strong paratergal and parasternal dashes on segments VII–IX, on anterior segments only parasternal spots.
Morphology. For habitus, see Fig. 1.
Head: Antenna not dilated at the base, the long apical part very thin (Fig. 2d).
Thorax: Prosternal ridges forming a narrow or very narrow isosceles triangle with straight sides (except for the basal quarter) and a sharp tip. Ridges strongly blackish brown coloured (Fig. 2c).
Abdomen: Tergum II without a finger-like process (Fig. 1a). Lateral filaments VII–IX short triangular or very short.
Genitalia and sternum IX as in Figs. 2a, 3. Posterolateral processes of segment IX short triangular, blunt. Penis lobes very long and narrow, sides nearly parallel or only slightly converging apically, penis shaft narrow at the attachment point. Apophyses of styliger sclerite inconspicuous. Central sclerite narrow and elongated, apically more or less acute. Lateral sclerite band-shaped, oblique, connected to the central sclerite by a thin, horizontal strip. Forcipes long, slightly tapered towards the tip, apical third more or less bent medially; with a narrow apical tuft of thin spines (Fig. 2b). Strong black pigmentations as in Fig. 1a, left side. Sclerites and forcipes show a brown colouring; the lateral sclerites are the most strongly coloured, almost blackish brown.
Remarks
The forcipes of C. longilobata sp. n. are equipped with an apical tuft of spines (see Malzacher 2022a; forceps type 4). Within this forceps type, C. longilobata sp. n. belongs to the TP lineage (Malzacher 2022a), with long and more or less triangular penis lobes but without a dilated antennal base. Caenis longilobata sp. n. can be distinguished from all other species of this lineage by the following combination of characters: Genital sclerites and forcipes coloured; penis lobes very long and narrow, with nearly parallel sides; central sclerite long and narrow; prosternal triangle apically sharp-pointed; ratio of length of forceps tuft [Fig. 2b (2)]: length of forceps shaft [Fig. 2b: (1)] = 1:8.
Fig. 2.
Caenis longilobata sp. n., male imago. a. Genitalia. b. Forcipes (1: length of forceps shaft; 2: length of apical tuft of spines.). c. Prosternal triangle. d. Antennal scape, pedicel and base of flagellum.
Caenis jinjana Kimmins, 1956
(Fig. 4)
Kimmins (1956: 84, sub Caenodes jinjana); Thew (1960: 199, sub Caenodes jinjana); Demoulin (1970: 157, sub Caenodes jinjana); Malzacher (1993: 398); Malzacher (2011: 53).
Material examined
Western Uganda, Kabarole district, Kalitutsi Lodge, 0.663375N 30.267559E, 1525 m, 21.09.2022, 4 ♂♂ imagines in 75% EtOH, leg. W. GRAF. Inventory number SMNS_ EPH_011998_A.
Remarks
For detailed redescriptions, see Malzacher (1993, 2011). The specimens observed here show melanism (Fig. 4), which had not been observed in this species before. Diagnostic characters are often variable in different populations of this species. Therefore, it cannot be excluded that separate subspecies, possibly even different species, are involved. This can, however, only be clarified by extensive rearing of male nymphs from different populations, or possibly by molecular investigations.
Acknowledgements
My special thanks go to Wolfram Graf (Universität für Bodenkultur, Vienna) for leaving me the material for investigation. I am also indebted to Milan Pallmann (SMNS) for taking the macro-photographs. Thanks to Helen James (National Museums Northern Ireland) and Arnold H. Staniczek (SMNS) for useful comments which improved the manuscript, and to Daniel Whitmore (SMNS) for his thorough editing.
© Staatliches Museum für Naturkunde Stuttgart
