Trechosia humeralis, Geginat, Gernot, 2007

Geginat, Gernot, 2007, A new species group of the genus Trechosia from the Cape region of South Africa (Coleoptera, Carabidae, Trechinae), Zootaxa 1469, pp. 43-50 : 48

Trechosia humeralis comb.nov.

(= Plocamotrechus humeralis Jeannel, 1930 , = Cothresia humeralis (Jeannel, 1930))

This species was originally described as Plocamotrechus humeralis ( Jeannel 1930) but was later transferred by Jeannel (1964) into the genus Cothresia . I here repeat the characteristics of this species which fit well into the definition of the T. intermedia species group designated above. It shows much more similarity to T. intermedia than to C. curta the type species of the genus Cothresia and therefore is transferred to the genus Trechosia . The species is only known in the single female type specimen from the vicinity of Cape Town.

Differential diagnosis. Size intermediate between T. intermedia and T. kogelbergensis . In contrast to T. intermedia and T. kogelbergensis apical end of the scutellar stria converging towards the elytral suture and striae 5 and 6 as well marked as the 4th stria. Elytral microsculpture of the sutural interval slightly more transverse than in T. intermedia but much less transverse than in T. kogelbergensis .

Description. Similar to T. intermedia from which it differs as follows: Length (measured from apex of elytra to anterior edge of labrum) 3.8 mm. Colour of body and appendages similar to T. intermedia but antennomeres brown, scape and bases of antennomeres 2–11 lighter reddish brown ( Fig. 3 A). Pronotum: length 0.8 mm, width 1.0 mm, length/width ratio 0.8. Elytra: length 2.2 mm, width 1.6 mm, length/width ratio 1.4. Scutellar stria shorter, converging towards suture, ending well before level of anterior discal setiferous puncture. Striae 1–6 neatly impressed, well marked towards apex. Striae 1–3 effacing between base and anterior setiferous puncture, striae 4–6 not effacing towards base of elytra. Stria 7 partly effaced. Microsculpture of elytra in sutural interval slightly more transverse than in T. intermedia , slightly more transverse in 1st (sutural) than in 2nd interval, length/width ratio of mesh in sutural interval approximately 2:1 ( Fig. 3 B). Macropterous. Aedeagus unknown.

Material examined. Holotype female: “Cape Town, Dr. Purcell” [the unique type specimen preserved in the Muséum National d'Histoire Naturelle, Paris, France ( MNHN) was examined]

Remarks. The precise type locality of T. humeralis is not known. Without citing a specified source Jeannel suggests that the type locality of T. humeralis is probably the forest area around Stellenbosch, 20 km east of Cape Town ( Jeannel 1964). In its morphological characteristics (e.g. size, microsculpture) T. humeralis lies between T. kogelbergensis and T. intermedia . This intermediary position of T. humeralis correlates well with the type locality “Cape Town” of T. humeralis which is situated geographically between the Cedarberg 160 km north of Cape Town and the Kogelberg 40 km east of Cape Town.

Figures

FIGURE 3. Trechosia humeralis (Jeannel, 1930), holotype, female. General habitus (A), microsculpture of elytra between the anterior and posterior discal setiferous punctures (B).