Hercostomus brandbergensis, Grichanov, 2020

Grichanov, Igor Ya., 2020, New species of Hercostomus Loew, 1857 from Afrotropics (Diptera: Dolichopodidae) and key to Afrotropical fauna, European Journal of Taxonomy 722, pp. 16-36 : 18-20

Hercostomus brandbergensis sp. nov.

urn:lsid:zoobank.org:act:4EC8CD95-806F-4971-A799-A461C7422AEE

Fig. 1

Diagnosis

Having simple fore tarsus, the new species is close to H. nectarophagus Curran, 1924 , differing distinctly in male mid and hind femora each with ventral row of erect cilia, about as long as diameter of femur. Hercostomus nectarophagus males have no long ventral cilia on femora ( Grichanov 1999). The hypopygia are rather species-specific in the two species.

Etymology

The species is named after the type collection locality: the Brandberg Massif.

Material examined

Holotype

NAMIBIA • ♂; Brandberg , Mason Shelter; 21°04′39′′ S, 14°05′43′′ E; 1750 m a.s.l.; 5–14 Mar. 2002; A.H. Kirk-Spriggs and E. Marais leg.; Malaise trap, riverbed; NMNW.

Paratype

NAMIBIA • 1 ♂; same collection data as for the holotype; terminalia dissected, stored in glycerin in microvial pinned with source specimen; NMNW .

Description

Male ( Fig. 1 )

MEASUREMENTS (in mm). Body length 3.6; antenna length 0.8; wing length 2.9; wing width 1 ( Fig. 1A ).

HEAD. Frons greenish black, densely white pollinose; face black, densely white pollinose. One long, strong, vertical pair of ocellar setae; 1 short, postvertical pair of ocellar setae. Upper postocular setae black; lateral, lower ones white. Eye with short hairs; face glabrous. Face gradually narrowed towards palpi, 3.9 × as high as wide in middle, under antennae about 1.2 × as wide as width of postpedicel, at clypeus 0.7 × as wide as width of postpedicel; clypeus not reaching lower margin of eyes. Antenna ( Fig. 1B ) slightly longer than height of head, entirely black; pedicel short, wide, internally convex anteriad, with short distal setulae; postpedicel asymmetrical, elongate, narrowed, angular apicodorsally, shorter than high (7 ⁄ 8), covered with short pubescence; arista mid-dorsal, black, with short hairs. Length ratio of scape to pedicel to postpedicel to stylus (1 st – 2 nd segments), 8/9/14/8/52. Palpus, proboscis moderately small, brown, with short black setae; palpus with 1 black bristle.

THORAX. Greenish black, greyish pollinose; mesonotum shiny. Six strong dorsocentral setae; 2 rows of acrostichals, nearly half as long as dorsocentrals; 2 strong notopleural, 1 strong humeral, 1 posthumeral setae. Propleura with 1 strong black seta above fore coxa, 2 groups of short light hairs. Scutellum with 2 strong setae, 2 lateral hairs.

LEGS. Including coxae mostly yellow; mid coxa with brown lateral strip; hind femur brown at extreme apex; hind tibia brownish distally; tarsi black from tip of basitarsus, hind basitarsus brown-black. Fore coxa with black hairs anteriorly, several setae in apical half; mid coxa with 1 strong lateral seta in addition to anterior hairs; hind coxa with 1 strong lateral seta. Fore femur without long hairs. Fore tibia with 2 short posterodorsal setae, fore tarsus simple. Length of fore femur to tibia and tarsomeres 1–5 = 0.93 mm, 0.89 mm, 0.49 mm, 0.21 mm, 0.15 mm, 0.14 mm, 0.11 mm. Mid femur with 1 anterior, 1 posteroventral subapical seta, with ventral row of 6–8 dark erect curved cilia, longer than diameter of femur ( Fig. 1C ). Mid tibia with 3 anterodorsal, 2 posterodorsal, 5 apical setae. Length of mid femur to tibia and tarsomeres 1–5 = 1.12 mm, 1.25 mm, 1.16 mm, 0.58 mm, 0.47 mm, 0.26 mm, 0.14 mm. Hind femur with one subapical anterior seta, with ventral row of 5–6 dark erect cilia, about as long as diameter of femur. Hind tibia with 2 anterodorsal, 3 posterodorsal, 5 apical setae. Hind tarsomeres 1–2 with 1–2 short apical setae. Length of hind femur to tibia and tarsomeres 1–5 = 1.4 mm, 1.6 mm, 0.39 mm, 0.44 mm, 0.28 mm, 0.18 mm, 0.21 mm.

WING. Simple, greyish, almost hyaline, veins brown. Costa simple. R 1 reaching to first third of wing length. R 2+3, R 4+5 weakly divergent. Ratio of part of costa between R 2+3, R 4+5 to between R 4+5, M 1+2: 40/13. R 4+5, M 1+2 slightly convergent in distal part; M 1+2 joining costa at wing apex. Crossvein dm-m straight, forming right angle with both M 1+2 and M 4 longitudinal veins. Ratio of dm-m to distal part of M 4: 27/49.

Posterior wing margin almost evenly convex. Anal vein distinct, almost reaching wing margin; anal lobe narrow; anal angle obtuse. Lower calypter yellow, with black setae. Halter yellow.

ABDOMEN. Greenish black, weakly pollinose, with black hairs, marginal setae. Segment 7: ¾ length of epandrium. Segment 8 large, covering more than half lateral side of epandrium, with numerous fine dark setae. Genitalia ( Fig. 1D ) with epandrium brownish black, rounded-oval, nearly 2× longer than high. Foramen positioned before middle of left lateral side. Hypandrium mid-ventral, with short base projecting distoventrally, 4 long thin lobes of different lengths, 1 very broad lobe ( Fig. 1E ). Phallus thin, projected. Distoventral epandrial lobe fused to epandrium, projected, with 2 short, 1 very long apicoventral epandrial setae. Surstylus yellow, bilobate, with narrow lobes of different lengths. Distal lobe of postgonite as long as ventral lobe of surstylus, narrow, slightly curved ventrally at apex. Ventral lobe of postgonite strongly sclerotized, simple, directed distally, with serrate ventral margin. Cercus ( Fig. 1F ) yellow, with short light hairs, with large basolateral lobe bearing 3 long and several short setae and long narrow apex bearing 4 long pedunculate setae.

Female

Unknown.

Ecology

The Brandberg Massif is an isolated mountain range in western Namibia on the eastern edge of the Namib Desert, located in the Nama Karoo Biome. The type locality “Mason Shelter” (1800– 1750 m a.s.l.) is a more or less flat open plain, dissected by some small riverbeds and fringed by rocky hills with huge boulders and rock slabs. It contains some single trees of Acacia hereroensis Engl. , Ficus sycomorus L. and Ozoroa crassinervia (Engl.) R.Fern. & A.Fern. , abundant small trees of Commiphora saxicola Engl. and scattered individuals of Sterculia quinqueloba (Garcke) K.Schum. , Galenia africana L., Eriocephalus dinteri S.Moore and Cyphostemma currorii (Hook.f.) Desc. at the southern margin of the plain. In addition, low shrubs of Salsola sp. are evenly dispersed throughout ( Koch 2006). The Hercostomus brandbergensis sp. nov. type specimens were collected by Malaise trap installed in one of the riverbeds.

Distribution

Namibia.

Figures

Fig. 1. Hercostomus brandbergensis sp. nov., ♂, paratype (NMNW). A. Habitus. B. Antenna. C. Mid femora, anterior view. D. Hypopygium, right lateral view. E. Distoventral appendages of epandrium. F. Cercus, surstylus and distal lobe of postgonite.