Trachusa namibiensis, Kasparek, 2018

Kasparek, Max, 2018, A new species of Trachusa Panzer, 1804 (Megachilidae: Anthidiini) from southern Africa, with notes on the subgeneric classification and a key to the Afrotropical species, Zootaxa 4399 (3), pp. 329-340 : 332-338

Trachusa namibiensis sp. n.

( Figs 1–6 )

Type material. All material had originally been deposited in the Albany Museum ( AMG). Paratypes have been donated to the museum collections in Berlin ( ZMB), London ( NHMUK) and Kansas ( SEMC).

Holotype: Male. NAMIBIA, WNW Omatjete (20.57°S, 15.14°E), 15.iii.2004, F. W. and S. K. Gess leg. (Nos. 75595) ( AMG) . Paratypes (21 ex.): NAMIBIA: 1 ♀ 47 km from Kamanjab by road to Palm (19.37°S, 14.26°E), 30.iii.1997, F. W. and S. K. Gess leg. (No. 75588: AMG) .— 1 ♂ 5 km S of Palmwag (19.54°S, 13.58’E), 27.iii.2004, F. W. and S. K. Gess leg. (No. 75587: SEMC) .— 1 ♀ between Palm and Khorixas (20.17°S, 14.05°E), 31.iii.1997, F. W. and S. K. Gess leg. (No. 75590: AMG) .— 7 ♀ circa 15 km south of Swartbooisdrif (17.27°S, 13.46°E), 23.iii.2004, F. W. and S. K. Gess leg. (No 75597: SEMC, No 75598: NHMUK, No 75599: NHMUK, No 75600: SEMC, No 75601: ZMB, No 75602: SEMC, No 75603: AMG) .— 1 ♀ WNW Omatjete (20.57°S, 15.14°E), 15.iii.2004, F. W. and S. K. Gess leg. (No. 75596) ( AMG) .— 3 ♀, 1 ♂ Gaub / Kuiseb passes (23.27°S, 15.46°E), 13.iii.2000, F. W. and S. K. Gess leg. (No 75591: ZMB, No 75592: ZMB, No 75593: AMG, No 75594: AMG) .— 5 ♀, 1 ♂ near Two Palms , Uniab River (19.53°S, 13.54°E), 27–28.iii.2004, F. W. and S. K. Gess leg. (No 75604: ZMB, No 75605: AMG, No 75606: AMG, No 75607: AMG, No 75608: AMG, No 75609: AMG) .

Description. Female. Head. Black with yellow band on vertex ( Figs 1 , 2 ); clypeus densely and deeply punctured; side of clypeus convex, apical margin with semi-circular emargination ( Figs 1 , 4 ); mandible broad, black, with one large apical tooth and four irregular blunt subapical teeth ( Figs 1 , 5 ); tooth 2 and 3 (counted from inwards) often merged but still two distinguishable tips; subantennal suture nearly straight ( Figs 1 , 4 ); entire head with dark brown to black erect hairs, longer around antennal sockets; clypeus and paraocular area in most individuals dark black but in 2 out of 18 individuals upper half of clypeus and parts of paraocular area indistinctly yellow; maxillary palpus four-segmented (one short basal segment, two elongate and one short apical segments) ( Fig. 6e ).— Mesosoma: Black, polished with L-shaped yellow band on scutum anterolaterally ( Fig. 1 ); distance between punctures much larger in middle and anterior parts (distance between punctures equal to their diameter and more) than laterally (distance mostly half their diameter or less); lateral margin of scutum carinate; scattered dark brown to black erect pubescence; scutellum broadly rounded with median emargination ( Figs 1 , 5 ), mostly black, but sometimes with yellow stripe or yellow lightening on outer side; axillae entirely or partly yellow; pronotal lobe oval, margin carinate, usually black but some individuals bicoloured yellow-black; mesepisternum black, shining; omaulus sharply angular-shaped to carinate, carina extending onto ventral surface nearly to middle coxa.— Legs: Dark brown to black ( Fig. 2 ), some individuals with small yellow lightening in proximal part of tibiae (more than half of the specimens with at least some small yellow lightening on hind tibia, more rarely also on fore and mid tibiae); width of tibia at widest point: fore tibia 0.75 mm, middle tibia 1.07 mm, hind tibia 1.09 mm (average values) (cf. Figs 6b, 6c ); small arolium present.— Metasoma: T1–T4 black with yellow to brownishyellow sides; yellow area with dark spot; T5 and T6 entirely brownish-yellow (T6 darker than T5), sometimes with some black maculation ( Fig. 1 ); terga with black, erect, scattered pubescence; scopa ochraceous to reddish-brown. S1–S5 reddish-brown, S6 black.

Male. Head. Clypeus yellow, slightly convex, with black (holotype) to brownish-transparent crenulation on apical margin, wider laterally than in middle ( Fig. 1 ); clypeus emarginate medially ( Figs 1 , 5 ); mandible yellow, lower side brown, teeth black ( Fig. 1 ); one large apical and two smaller subapical teeth, the latter two separated by deep rounded emargination ( Fig. 5 ); condylar ridge conspicuous; lower paraocular area yellow up to upper edge of antennal socket; supraclypeal area mostly yellow, upper margin W-shaped; subantennal suture slightly arcuate outwards ( Fig. 4 ); vertex with broad yellow transverse band extending onto upper genal area ( Fig. 1 ); antenna dark brown, front side of scape yellow; long white pubescence on underside of head, around antennal socket, on paraocular area and laterally on clypeus; other parts with only scattered pubescence.— Mesosoma. Pronotal lobe bicoloured (black proximally, yellow distally) with strong carina; scutum black and shining with anterolateral yellow L-shaped band ( Figs 1 , 2 ); punctation shallow, more sparse medially than laterally (punctures widely separated in the middle, many of them separated by 2–3 times their diameter; laterally, distance between punctures usually only half their diameter or less); omaulus sharply angular-shaped to carinate, carina extending on to ventral surface of thorax close to middle coxa; scutellum broadly rounded, with shallow emargination medially ( Fig. 5 ); yellow band on distal side, interrupted medially; proximal side black; axilla entirely yellow ( Fig. 1 ).— Legs: Femora dark brown to black with yellow longitudinal stripes; tibiae on outer sides yellow with some ill-defined brown maculation, inner sides brown; middle tibia drop-shaped, middle basitarsus slender, flat; width of tibiae at widest point: fore tibia 0.75–0.81 mm (holotype: 0.78 mm), middle tibia 1.05–1.20 mm (holotype: 1.20 mm), hind tibia 0.97–1.07 mm (holotype: 1.05 mm); mediotarsal segments brown; pulvilli small.— Metasoma. T1 and T2 with one yellow band on each side; T3 yellow with broad V-shaped black emargination; T4–T7 yellow ( Fig. 1 ); T1–T5 with narrow light brown stripe within yellow area laterally; T6 emarginate apicomedially, with apical carina; T7 small, crescent-shaped, curled under metasoma (visible only ventrally); apical margin of S2 convex, with fringe of long hair in middle of outer margin; S3 with median emargination, dense fringe of hair at margin ( Fig. 3 ); S4 broadly emarginate with black marginal comb of approximately 20–30 bristles on each side; S5 with black comb of almost same size as that on S4. Combs on S4 and S5 run diagonal to each other; gonoforceps deeply bifid, Yshaped ( Fig. 6d ); apex of longer arm spoon-like, flattened and pointed, with dark brown margins; shorter arm broader, with thickened apex.

Differential Diagnosis. Of the six sub-Saharan species of Trachusa , males are only known for T. schoutedeni , T. aquiphila , and T. namibiensis sp. n.

The general appearance of Trachusa namibiensis sp. n., particularly the male, superficially resembles Trachusa aquiphila , the only other species of Trachusa known from southern Africa, although both species can be distinguished by a number of characters ( Table 2).

The female of T. namibiensis sp. n. is distinguished from T. aquiphila by a number of characters including the bilobed apical margin of the clypeus (dentate to crenulated margin without emargination in T. aquiphila ), the black, shining head and mesosoma with short, black, erect bristles (relatively long, golden pubescence in T. aquiphila ), T1–T4 with one lateral ochraceous stripe on each side (uninterrupted, ochraceous transverse bands on T1–T 4 in T. aquiphila ). The male of T. namibiensis sp. n. is distinguished from T. aquiphila by the shape of the clypeus and paraocular area, which is slightly convex in T. namibiensis sp. n. (clypeus medially strongly protuberant with flat sides and flat paraocular area in T. aquiphila ), the scutum is shining with punctures separated by half their diameter in T. namibiensis sp. n. (in T. aquiphila the scutum is dull with dense, contiguous or sub contiguos punctation), pubescence of upper side of head, meso- and metasoma is sparse with short, erect hairs in T. namibiensis sp. n. (long ochraceous hairs in T. aquiphila ), tibiae yellow with inconspicuous light brown oblong maculation in T. namibiensis sp. n. (yellow with dark brown oblong maculation in T. aquiphila ), and the terga have one yellow maculation on each side of T1–T 2 in T. namibiensis sp. n. (transverse bands in T. aquiphila ).

The female of Trachusa namibiensis sp. n. is distinguished from T. eburneomaculata by the bilobed apical margin of the clypeus (apical margin widely rounded and crenulate in T. eburneomaculata ), the presence of a yellow stripe on the vertex (one yellow spot on each side of vertex in T. eburneomaculata ), and a sparse, short, black and erect pubescence on head and mesosoma ( T. eburneomaculata has long, dense, white pubescence on head and sides of mesosoma and a patch of white hair in middle of anterior side of scutum).

The female of Trachusa namibiensis sp. n. is distinguished from T. flavorufula by the number of mandibular teeth (one large and four small blunt teeth in T. namibiensis sp. n.; one large and six small, blunt, different-sized teeth in T. flavorufula ), the colouration of scutum, scutellum and axillae, and in particular by the colour of the terga (see key).

The female of Trachusa namibiensis sp. n. is distinguished from T. massauahensis by the ground colour of the integument (black in T. namibiensis sp. n., reddish to reddish-brown in T. massauahensis ), the colour pattern of the terga (T5–T6 ochraceous in T. namibiensis sp. n.; T. massauahensis T5 has on each side one lateral ochraceous stripe, T6 without ochraceous markings).

The male of T. schoutedeni is distinguished from T. namibiensis by the presence of a long, rod-shaped projection arising from the underside of the head, a bicoloured (black and yellow) clypeus (entirely yellow in T. namibiensis sp. n.) and the distinct colour pattern of the metasomal terga (yellow colouration confined to T 1 in T. schoutedeni , T1–T7 with yellow in T. namibiensis sp. n.). The female of T. schoutedeni is distinguished by the colouration of the terga (yellow band on T1, the other terga are dark, while yellow on all terga in T. namibiensis sp. n.), and yellow longitudinal stripes on tibiae (entirely black in T. namibiensis sp. n.).

Seasonal occurrence. Found on the wing so far only in the second half of March, i.e., autumn in Namibia.

Flower preferences. Trachusa namibiensis sp. n. was collected on the flowers of Acanthaceae ( Monechma cleomoides (S. Moore) C. B. Clarke ); Brassicaceae (Cleome) ; Fabaceae (Adenolopus pechuellii (Kuntze) Torre & Hillc., Crotalaria sp., Indigofera filipes Benth. ex Harv. ); Lamiaceae ( Hemizygia floccosa Launert ) and Pedaliaceae (Sesamum) . There was a wide spectrum of variation in the colour of the flowers visited, which included pink, white, yellow, orange, violet and mauve.

Remarks. Michener (2007: 535) noted in a chapter on the subgenus Massanthidium that “an additional species is represented by a specimen from Namibia ”. Also Eardley et al. (2010) mentioned a hitherto undescribed species of Trachusa (Massanthidium) from Namibia. It is not clear whether these statements refer to the same material. The specimens on which these statements were based could not be located.

Significantly, the series of T. namibiensis sp. n. collected by F. W. and S. K. Gess included also a male T. aquiphila , which was labelled by the collectors as “ Trachusa (Massanthidium) sp. (undescr.) male, det. F. W. Gess 2000”.

Whereas the maxillary palpus is normally four-segmented, there also seem to be three-segmented individuals, but the small apical segment may be broken off in those individuals.

Figures

FIGURE 1. Trachusa namibiensis sp. n. A–B. Dorsal habitus A. female paratype. B. male holotype. C–D. Head. C. female paratype. D. male holotype (D).

FIGURE 2. Trachusa namibiensis sp. n. Lateral habitus. A female paratype, B male holotype.

FIGURE 3. Trachusa namibiensis sp. n.: A–B. Hind leg. A. Female paratype. B. Male holotype. C. Male ventral side of metasoma.D. Female apical sterna. Note the black sternum S6.

FIGURE4. Head of Trachusa namibiensis sp. n. Left female,right male.Note the outwardlyarcuate subantennal suture in the male (as indicated by the thin, straight line).

FIGURE5.Trachusanamibiensis sp.n.:Comparison of scutellum/axillae,clypeusandmandibleof female (left)andmale (right).

FIGURE 6. Trachusa namibiensis sp. n. Note that the dotted area in male tergum T7 (a) represents a transparent area (the major part of T7 is yellow and opaque).The apex of the longer arm of the gonoforceps (d) has an almost spoon-like shapewith dark brown margins.