Microphontes gaiophanes, Markee, Amanda & Dikow, Torsten, 2018

Markee, Amanda & Dikow, Torsten, 2018, Taxonomic revision of the assassin-fly genus Microphontes Londt, 1994 (Insecta, Diptera, Asilidae), African Invertebrates 59 (2), pp. 195-237 : 195

Microphontes gaiophanes sp. n. Figs 1-2, 9-10, 11-16, 17-20, 21-25, 62-63, 72

Etymology.

Greek gaiophanes = earth-coloured. Refers to the beautiful earth tone colouration of this species.

Diagnosis.

The species is distinguished from congeners by the more or less square abdominal tergites, the short macrosetose dorsal anepisternum, the extensively macrosetose ante- and postpronotum, the overall brown colouration and the grey pubescent female abdominal tergite 8.

Description.

Head: wider than high, brown; vertex and compound eyes at same level; facial swelling indistinct, only lower facial margin slightly developed, silver pubescent; mystax white macrosetose, restricted to lower facial margin, short, reaching tip of proboscis; ommatidia of same size; postgena posterior margin simple, smooth; frons (at level of antennal insertion) slightly diverging laterally, greyish-brown pubescent, light brown macrosetose; ocellar tubercle brown pubescent, light brown setose; vertex brown pubescent, yellowish to light brown macrosetose; median occipital sclerite (m ocp scl) with several yellowish macrosetose; postocular (pocl) setae slightly angled anteriorly distally, yellowish macrosetae; occiput predominantly grey pubescent, yellowish setose; compound eye posterior margin (in lateral view) straight or slightly curved throughout.

Proboscis and maxillary palpus: proboscis straight, dark brown; postmentum plate-like, straight, ventral margin entirely smooth, white setose ventrally; prementum circular, with dorso-median flange, asetose; labella reduced, fused to prementum only ventrally, only forming distal tip of proboscis, rounded; maxillary palpus brown, two-segmented, long yellowish setose, cylindrical; stipites fused medially, but with V-shaped indentation, apubescent, long white setose.

Antenna: light brown, lightly grey pubescent; scape 1.5 × as long as pedicel, short and long yellowish setose and macrosetose ventrally; pedicel short yellowish setose ventrally and dorsally; postpedicel cylindrical (same diameter throughout), 1.5 × as long as scape and pedicel combined, asetose; stylus comprised of 1 element, 0.28 × as long as postpedicel, asetose; apical seta-like sensory element situated apically on stylus.

Thorax: brown, postpronotal lobes and lateral scutum orange to light brown; prosternum grey pubescent, separated from proepisternum, square to rectangular in shape (straight dorsally); proepisternum grey pubescent, long yellowish macrosetose; cervical sclerite long yellowish setose; antepronotum grey pubescent, short yellowish setose and long yellowish macrosetose; postpronotum grey pubescent, long yellowish macrosetose medially and laterally, long yellowish setose sub-laterally; postpronotal lope short and long yellowish macrosetose; pleuron grey pubescent; proepimeron short yellowish macrosetose anteriorly; anepisternum short yellowish macrosetose dorsally, supero-posteriorly short yellowish macrosetose (indistinguishable from other dorsal anepisternal setation); anterior basalare short yellowish setose dorsally, posterior basalare asetose; anepimeron asetose, katepisternum predominantly asetose, postero-dorsally yellowish setose, katepimeron asetose, katatergite white setose and long yellowish macrosetose, meron + metanepisternum asetose, metakatepisternum asetose, metepimeron asetose, anatergite asetose; scutum predominantly grey pubescent, antero-sublaterally weakly grey pubescent (almost appearing apubescent), median longitudinal stripe and medio-laterally brown pubescent, scutum setation: short light brown setose, setae with small sockets, 2 npl setae, 1-2 spa setae, 2 pal setae, 3-4 long yellowish postsutural dc macrosetae, acr setae short brown presuturally and postsuturally, median posterior scutum (between dc setae) asetose; scutellum grey pubescent, ds sctl setae absent, ap sctl setae present, 6-8 long light brown macrosetae; postmetacoxal area entirely membranous.

Leg: light brown to brown, apubescent, all setae circular in cross section; pro coxa dark brown proximally, light brown distally, grey pubescent, white setose and macrosetose; pro femur brown, short white setose, yellowish macrosetose: 1 anterior proximally, 1 postero-dorsal distally, 1 dorsal distally; pro tibia light brown to brown, short white setose, yellowish macrosetose: 4 in 1 antero-dorsal row, 4 in 1 dorsal row, 2 in 1 posterior row, 3 in 1 postero-ventral row, distal tip with 5-6 long yellowish macrosetae; mes coxa brown, grey pubescent, white setose and yellowish macrosetose; mes femur brown, short white setose, yellowish macrosetose: 1 antero-dorsal proximally, 1 antero-dorsal distally, 1-2 dorsal distally; mes tibia light brown to brown, short white setose, yellowish macrosetose: 4 in 2 dorsal rows, 3 in 1 antero-ventral row, 3 in 1 postero-ventral row, distal tip with 5 long yellowish macrosetae; met coxa brown, grey pubescent, white setose and macrosetose, anteriorly without any protuberance; met trochanter yellowish macrosetose, cylindrical, medially without any protuberance; met femur brown, short white setose, yellowish macrosetose: 3-4 in 1 anterior row, 1 proximal ventrally, 2 distal dorsally, 3 apical dorsally; met tibia brown, straight, short white setose, yellowish macrosetose: 4 in 1 anterior row, 3 in 1 antero-ventral row, 4 in 1 dorsal row, distal tip with 6 long yellowish macrosetae; proximal pro, mes and met tarsomeres longer than following 2 tarsomeres combined, proximal met tarsomere as wide as following tarsomeres; pro tarsomeres 1-5 white setose dorsally, tarsomeres 1-4 long yellowish macrosetose disto-laterally and disto-dorsally, tarsomere 5 weakly yellowish macrosetose distally; mes tarsomeres 1-5 white setose dorsally, tarsomeres 1-4 long yellowish macrosetose disto-laterally and disto-dorsally, tarsomere 5 weakly yellowish macrosetose distally; met tarsomeres 1-5 white setose dorsally, tarsomeres 1-4 long yellowish macrosetose disto-laterally and disto-dorsally, tarsomere 5 weakly yellowish macrosetose distally; pulvilli well-developed (as long as claw); claw abruptly angled distally, pointed; empodium setiform, approximately ½ length of claw.

Wing: 4.2-5.5 mm.

Abdomen: shape regular, T2-3 somewhat square (length to width ratio = 1:1.2), brown to black, laterally orange to light brown, tergites smooth, setae with small sockets only; T1 yellowish setose, postero-laterally long yellowish macrosetose, grey pubescent, anterior ¼, except laterally, membranous, dorsal surface smooth, without protuberances; T2-8 entirely sclerotised, brown, grey pubescent: in dorsal view appearing brown pubescent medially (area broader anteriorly) except distal margin, in lateral view appearing brown pubescent on dorsal surface, short yellowish setose, long yellowish setose antero-laterally on T2, marginal macrosetae absent from T2-8, medial macrosetae absent from T2-8; S1-8 dark brown, lightly grey pubescent, short yellowish setose.

Female (Figs 21-25): T6-8 grey pubescent, setation directed anteriorly on T6-7 and dorsally on T8; postero-paramedian T8 pores present, distinct, opening slightly elevated above tergite surface; T8 without any internal apodeme anteriorly; T10 divided into 2 heavily sclerotised acanthophorite plates, with 8-9, dark brown acanthophorite spines per plate; 3 spermathecae, median spermatheca larger than lateral ones, reaching anterior end of segment 7; common spermathecal duct very long, extending well beyond tip of genital fork ( S 9, furca), individual spermathecal ducts short; spermathecal reservoirs formed by more or less expanded ducts to sac-shaped reservoir, heavily sclerotised; genital fork ( S 9, furca) formed by single, inverted Y-shaped sclerite, median sclerite (at posterior tip) absent, anterior apodeme present, short plate-like apodeme.

Male (Figs 17-20): T1-T8 and S1-S8 entire (without modifications); hypopygium black, rotated by 90°; hypandrium well-developed, triangular, posterior margin with long postero-median projection; gonocoxal apodeme present, short, entirely confined to hypopygium; phallus very short, tip at level of origin of gonostyli, 1 phallic prong, tip pointed, without any protuberance.

Type locality: NAMIBIA: Erongo: Namib-Skeleton Coast National Park, off C14, 23°34'22"S, 015°48'37"E (-23.57278, 15.81028).

Material examined.

NAMIBIA: Erongo: 1♀ 12♂ Namib-Skeleton Coast National Park, off C14, 23°34'22"S, 015°48'37"E, 922 m, 2017-09-26 collected a.m. (9:00-noon), sparsely vegetated sand dune, perching on sand, Dikow, T. (1♂ Holotype USNMENT01384029 , NMNW; 1♂ Paratype USNMENT01384061 , NMNW; 8♂ Paratypes USNMENT01384037 , USNMENT01384047 , USNMENT01384049 , USNMENT01384080 , USNMENT01384082 , USNMENT01384092 , USNMENT01384118 , USNMENT01384134 , USNM; 1♀ nontype USNMENT01384499 , USNM; 2♂ nontype USNMENT01384419 , USNMENT01384459 , USNM) ; 4♀ Namib-Skeleton Coast National Park, off C14 , 23°34'22"S, 015°48'37"E, 922 m, 2017-09-26 collected a.m. (9:00-noon), sparsely vegetated sand dune, perching on low, dry vegetation, Dikow, T. (Paratypes USNMENT01384020 , NMNW; USNMENT01384008 , USNMENT01384018 , USNMENT01384130 , USNM) .

Distribution, biodiversity hotspots, phenology and biology.

Known only from the type locality (Fig. 72). A rarely collected species known only from a single collecting event in 2017 (Table 1). Adult flies are active in summer in an arid region on the eastern edge of the Namib Sand Sea (Table 2). Not known to occur in any biodiversity hotspot.

Biological data were gathered during observations in the field at the type locality. Male flies were more active and flew in a very specific pattern of an up-and-down flight, similar to a roller coaster, around the grass boulders or vegetation (see habitat in Figs 1-2). Furthermore, the male flies would land on the sand in open spaces between the grass boulders and perch or rest with their pro-, mes- and metathoracic legs held sideways and up (see Fig. 9). The females appeared less active and were observed to perch or rest on dry, low vegetation close to the grass boulders (Fig. 10, only a single female was collected perching on sand).