A new species of Phlugidia (Orthoptera: Tettigoniidae: Meconematinae) is described from the East Usambara Mts, Tanzania; a list is given of Saltatoria species occurring in the same habitat.
The East Usambara Mts are known for their high species diversity and degree of endemism. This high proportion of endemic species may be a result of the old age of the mountains, the long interval of separation from Central African forests and the stability of a continuous forest cover (Rodgers & Homewood 1982). Lowland forests, grading into submontane forest communities, offered sufficient habitats for speciation. Nowadays few areas of indigenous forest remain in the East Usambara, due to human use, especially clearing for tea plantations.
Over 20 Acridoidea and about 20 Ensifera species were originally described from the East and West Usambara Mts, many of them endemic, especially among the Ensifera (Bolívar I. 1906; Bolívar C. 1914; Descamps 1964, 1967; Griffini 1909; Hochkirch 1996; Jago 1982, 1983; Jin & Kevan 1991; Karny 1909; Karsch 1888, 1889, 1896; Ragge 1980; Ramme 1929; Sjöstedt 1909, 1913, 1929, 1931; Uvarov 1941, 1953).
Measurements of dimension in mm. Those of body length include male genitalia and the ovipositor of the female; the length of the ovipositor was measured from its base at the subgenital plate to its tip.
Phlugidia usambarica n. sp.
♂: Tanzania, East Usambara Mts, Sigi Trail, 450 m, Mar 1999 (C. Hemp coll.), depository NHML.
Tanzania, East Usambara Mts, 1 ♀, Sigi Trail, 450 m, Aug 2001 (C. Hemp coll.), depository NHML; 1 ♂, Sigi Trail, 450 m, Mar 1999 (C. Hemp coll.), depository EDNMK; 1 ♀, Sigi Trail 450 m, Aug 2001 (C. Hemp coll.), depository EDNMK.
Additional material examined.
Tanzania, East Usambara Mts, 3 ♂ ♂, 3 ♀ ♀, 2 nymphs, Sigi Trail, 450 m, Mar 1999, Aug 2001 (C. Hemp coll.).
Head: fastigium of vertex short; first antennal segments nearly touching medially. Eyes prominent and globular. Antennae more or less 4 times as long as body (Fig. 1).
Thorax: pronotum elongate, convex, about two times as long as wide seen from above; without carinae or median furrow; surface smooth and shiny. Pronotum inflated above elytra. Lateral lobes of pronotum shallow with small margin.
Wings: wings absent, tegmina partly covered by pronotum when folded together, posterior margin almost straight, visible from above.
Legs: front coxa bearing spine-like curved process pointing forward. Front femur with 3 spines, fore tibia with three inner and three outer spines, inner spines longer. First of these spines arising just below tympanal organ. Tympanal organs flat, open and non-conchate on both sides of the front tibiae. Midfemur unarmed, midtibia in its middle with single small ventral spur. Hind femur unarmed, hind tibia dorsally with a row of many small spines, hairy.
Abdomen: ninth abdominal segment with posterior margin triangular, spine-like apex slightly curved upwards (Figs 2, 3). Tenth abdominal tergite posterior margin has v-shaped notch (Fig. 3), lateral margins raised on each side, forming blunt processes at posterior margin (Figs 2, 3). Cerci slender, ending in an inner rounded lobe and a short outer one (Fig. 3). Subgenital plate almost square, styli tapering and curved downward (Fig. 5).
Males (n = 5). Measures in mm. Length of body: 9.8 to 11.0 (mean 10.3); median length of pronotum: 3.8 to 4.1 (mean 4.0); length of hind femur: 11.0 to 11.5 (mean 11.2); visible median length of elytra: 0.1 to 0.4 (mean 0.26).
Legs and part of abdomen greenish; eyes, base of hind femur, and a broad median line running on the pronotum to the abdomen's end, vivid iridescent turquoise blue. Head and lines beside blue median line, brown-reddish. Preserved insect greenish to tawny, reddish lines on pronotum, abdomen and head persistent.
Female: as male with following differences: pronotum shorter, flat, not raised in tegminal area as in male, tegmina not visible, even at sides of posterior margin of pronotum. Cerci very long and slender (1.4 mm), hairy (Fig. 7). Ovipositor inflated over basal half, up-curved, tips of valves dark pigmented (Fig. 7). Subgenital plate undivided, ending in finger-like projection (Figs 7, 8).
Females (n = 5). Measures in mm. Total length (with ovipositor): 11.0 to 14.8 (mean 12.7); median length of pronotum: 3.0 to 3.3 (mean 3.2); length of hind femur: 9.5 to 11.0 (mean 10.0); length of ovipositor: 5.0 to 5.3 (mean 5.1).
Habitat of P. usambarica and co-occurring Saltatoria species.
P. usambarica was collected in lush vegetation on large leaves of the submontane forests, about 1 to 2 m above the ground (Fig. 1). It was found along the Sigi Trail from altitudes of 450 to 900 m and on the Kwamkoro Nature Trail above Amani (900 m).
Saltatoria species living syntopically with P. usambarica in the vegetation (1 to 2 m) along the Sigi Trail include: Stenoschmidtia elegans (Decamps) (Eumastacidae), Rhainopomma usambarica (Ramme) (Lentulidae), Parepistaurus amanicus Uvarov (Acrididae, Coptacridinae), Dioncomena ornata Brunner v. Wattenwyl (Tettigoniidae, Phaneropterinae), Anthracites usambaricus Sjöstedt (Tettigoniidae, Conocephalinae, Agraeciini), Agraecia sp. (Tettigoniidae, Conocephalinae, Agraeciini), and Acauloplax exigua Karsch (Tettigoniidae, Pseudophyllinae). On the forest floor Ixalidium haematoscelis Gerstäcker (Acrididae, Catantopinae), Aresceutica subnuda Karsch (Acrididae, Catantopinae), Gymnoscirtus unguiculatus (Karsch) (Tettigoniidae, Mecopodinae) and Loveridgacris impotens (Karsch) (Pyrgomorphidae) were noted.
Along the Kwamkoro Nature trail (900 m) above Amani, Mastarammea karaseki (Ramme), R. usambarica, Parepistaurus amanicus occurred syntopically with P. usambarica; while on the forest floor Physocrobylus tessa Hochkirch, A. subnuda, and Ixalidium transiens Ramme were found.
Diagnosis and discussion
The genus Phlugidia was erected for the species Phlugidia africana Kevan, occurring on the Kenyan coast (Kevan & Jin 1993). This new genus was erected solely for geographical reasons, as it was the first species of Phlugidini found on the African continent.
The tribe Phlugidini was newly defined by Kevan & Jin (1993) containing, beside Phlugidia Kevan, the genera Phlugis Stål, Phlugiola Karny, and Tenuiphlugis Kevan. Gorochov (1998) added Asiophlugis. The key characters of the Phlugidini are a short vertex, which is declivent and not pointed, the eyes are prominently globosely protruding, the lateral lobes of the pronotum are shallow with no visible humeral sinus and the auditory foramen is small. The ovipositor is swollen in the basal part and the distal parts are strongly curved upwards.
The genus Phlugidia is characterized by minute thoracic spiracles and a thoracic auditory foramen which is virtually nonexistent. All sterna are unarmed. The tegmina are greatly reduced, to rounded lobes, and hind wings are absent. The front leg coxae bear a long spine-like process. Femora and tibiae have short spurs. The tympana are open, oval and flat. On the last abdominal segment posterior margins are notched with obliquely raised sides. The cerci are stout and straight.
The genus Phlugidia agrees closely with Phlugiola in general characters but differs in a more shallow lateral lobe of the pronotum, with the lower margin less convex, an obsolete thoracic foramen, a comparatively long anterior coxal process, greatly reduced tegmina that are covered by the pronotum, and femora tapering gradually from their widest points to their distal ends (Kevan & Jin 1993).
Kevan & Jin (1993) remark that Phlugiola dahlemica Eichler, known only from female greenhouse populations (Berlin, Germany, lost during the second world war) might well originate from Africa and not, as suggested previously, from South America, and thus might belong to the genus Phlugidia. Arguments given for this are a comparatively long coxal process of this species and hind femora that gradually narrow distally. These are characters of the genus Phlugidia. In Phlugiola the front coxal process is shorter or lacking and the hind femora are abruptly narrowed distally. A deeply bilobed female subgenital plate was listed by Karny (1907) as a generic feature for Phlugiola which was erected on the species Phlugiola redtenbacheri Karny. Females of P. dahlemica however have an entire subgenital plate with the posterior margin nearly straight. As Kevan & Jin (1993) had no females of P. africana they could not clarify the value of an entire or bilobed female subgenital plate serving as a generic character separating Phlugidia and Phlugiola.
P. usambarica as well has an entire subgenital plate but of a different shape with a smoothly rounded posterior margin (Fig. 7, 8) and this might now lead to the suspicion that another generic character separating Phlugiola and Phlugidia had been found, so justifying a shift of P. dahlemica to Phlugiola. However, in the meantime another Phlugiola species has been found in South America in which females have an entire subgenital plate (Nickle, in process). Thus the shape of the female subgenital plate cannot serve as a generic feature separating these two genera and the origin of Phlugiola dahlemica remains uncertain.
The differences between P. usambarica and P. africana lie in the shape of the male genitalia; the female of P. africana is hitherto unknown. The male cerci of P. usambarica lack the inner basal teeth present in P. africana and the cercal apices are more inflated and more strongly differentiated into two lobes (Fig. 4). The 10th abdominal segment is triangular with a v-shaped notch as in P. africana, but there are no lateral processes in P. africana. The posterior margin of the 9th abdominal tergum projects as a median spine-like process in P. usambarica, while it is triangular and without a process in P. africana (Figs 3, 4). The male subgenital plate is of square shape in P. usambarica (Fig. 5) and rectangular in P. africana (Fig. 6). The coloration of the living animal is a vivid iridescent blue, mixed with reddish and green, while P. africana shows a pattern of green and brownish (Kevan & Jin 1993).