Scaurotrechodes, Geginat, Gernot, 2006

Geginat, Gernot, 2006, A new flightless trechodine genus and species from the South African Cape region (Coleoptera: Carabidae: Trechitae), Zootaxa 1252, pp. 63-68 : 64-65

Scaurotrechodes gen.nov.

Type species

S. capensis sp.nov.

Diagnosis

Readily distinguished from all other Trechodini by the ovoid body shape with posterior angles of the pronotum and shoulders of elytra blunt and rounded ( Fig. 1 A). The head, despite being in its general appearance similar to that of Pachytrechodes bears a characteristic group of humps on the clypeus. Elytra without any trace of a sutural stria, which is very conspicuous in all other genera of the tribe. Mentum tooth broad, rounded, not bifid as in Pachytrechodes . Another characteristic feature of the new genus is the short stout protibia. Aedeagus not as filiform as in Trechodes , but also clearly more elongated and slender than in Pachytrechodes . In contrast to most other species of the tribe the internal sack of the aedeagus is inermous without prominent spines or sclerotized pieces.

Description

Body ovoid, surfaces glabrous, shiny. Head short, genae and tempora tumid, two supraorbital setae present, eyes well developed, glabrous. Clypeus with multiple humps; anterior part formed by bilobed protrusion, followed by central oval swelling, followed towards base of labrum by two laterally positioned small knobs bearing each one large seta. Mentum transverse, medially almost rectangularly recessed, mentum tooth broadly rounded. Suture between submentum and mentum tooth distinct and entire. Submentum near posterior edge on each side with a long forward projecting seta. Antennae moderately long, scape and antennomere 2 with a few long setae, antennomeres 3–11 pubescent. Penultimate palpomere of palps club­like, distally dilated, terminal palpomere laterally flattened, as long as penultimate palpomere in maxillary palps, much smaller and fusiform in labial palps. Penultimate palpomere of labial palps with 4 setae, two of them projecting from medial surface of palpomere. Tip of ligula elongated, with 2 long apical setae and 3 short lateral setae on each side. Pronotum not collared; anterior angles rounded; hind angles marked by seta but blunt and rounded, posterior border towards base with only a very slight sinuosity; without basal impressions. Epipleural rim between anterior angles and posterior seta present, effacing thereafter. Elytra ovoid, shoulders rounded, not discernable. Elytra with effaced vestigial scutellar stria and effaced elytral striae 2–5, no sutural stria discernible. Chaetotaxy of elytra regular; on elytral disc 1 basal setiferous puncture, 2 discal setiferous punctures in 3rd interval, and 3 apical setiferous punctures; series umbilicata in elytral rim regular with 4 subhumeral and 4 subapical setiferous punctures. Legs short, sturdy; protibia stout with a prominent apical spur; protibial cleaning organ well developed; proximal two tarsomeres of protarsi of the male enlarged. Aedeagus moderately elongated; basal part of median lobe formed by two separate lobes not fused dorsally; sclerotization of median lobe limited to basal part; internal sack without prominent spines or sclerotized pieces. Paramers with slender apical parts, each bearing five long setae at apex.

Etymology

Scaurotrechodes (m) from Latin scaurus, a, um (= with swollen ankles, clumpfooted), referring to the characteristic short and stout protibiae.

Remarks

The morphology of the aedeagus (basal part of the median lobe formed by two separate lobes) clearly defines Scaurotrechodes as a member of the subfamily Trechodinae. Among the three tribes of the subfamily Scaurotrechodes belongs probably to the Trechodini as it shows a number of characteristic features that are present in all (e.g. only ventral part of aedeagus sclerotized) or at least some genera (e.g. internal sack without enlarged spines or sclerotized pieces, effaced striation on elytra) of the tribe. On the other hand Scaurotrechodes . shows a number of characteristic features (humps on clypeus, effaced first stria, short stout protibiae) that clearly separate it from all other known genera of the tribe Trechodini and thus justify the erection of a new genus for this species. The effaced and rounded posterior angles of the pronotum are a feature that is shared with the Australian genus Cyphotrechodes Jeannel 1926 . As Scaurotrechodes differs in many other key features (e.g. striation of elytra, aedeagus), however, this similarity probably has to be considered as a convergent development among otherwise distantly related genera.

After Pachytrechodes from the Ulughuru mountains ( Tanzania) and Himalotrechodes Uéno 1981 from the Himalya, Scaurotrechodes is the third genus of the tribe that is localized to a small geographic range, flightless, and adapted to a hypogeic life style. The presence of another endemic African genus of the Trechodini that is like Pachytrechodes restricted to a geologically ancient mesic environment is biogeografically remarkable as it provides further support to the hypothesis that the Trechodinae represent relics from the ancient south continent Gondwana ( Jeannel, 1942).

Figures

FIGURE 1. Scaurotrechodes capensis gen. nov., sp. nov., holotype, male, from Dwarsberg, Grabouw, South Africa. General habitus (A), aedeagus dorsal view (B), aedeagus side view (C), left anterior tibia (D), and microsculpture (E) of right elytron between the anterior and posterior discal setiferous punctures.