Lachnocorynus chobeensis Hesse, 1969

Boschert, Claire & Dikow, Torsten, 2022, Taxonomic revision of the mydas-fly genera Eremohaplomydas Bequaert, 1959, Haplomydas Bezzi, 1924, and Lachnocorynus Hesse, 1969 (Insecta, Diptera, Mydidae), African Invertebrates 63 (1), pp. 19-75 : 19

Lachnocorynus chobeensis Hesse, 1969

Figs 41-46 , 47-49 , 55 , 56

Lachnocorynus chobeensis Hesse, 1969

GBIF: https://www.gbif.org/species/1591103

Lachnocorynus kochi Hesse, 1969 , syn. nov. ZooBank http://zoobank.org/F341EDA4-F1C6-4B14-8015-F95D23C30BF9. Original description online https://www.biodiversitylibrary.org/page/40724409

Diagnosis.

The species is distinguished from congeners by the wide face and vertex (similar width), the entirely apubescent anepimeron, and the sparsely grey pubescent abdominal tergites.

Redescription.

Female. Head: brown, facial gibbosity yellow, in general white pubescent, white setose, regular, cylindrical setae; width distinctly greater than thorax (at postpronotal lobe), interocular distance on vertex larger than at ventral eye margin; vertex between compound eyes ± horizontally straight, medially only slightly below dorsal eye margin, vertex white pubescent, white setose; ocellar triangle apubescent; facial gibbosity distinct, well-developed and discernible in lateral view, mystax covering entire facial gibbosity, white; parafacial area approximately as wide as ¾ width of central gibbosity (at same level); frons not elevated, medially apubescent, laterally white pubescent, white setose; occiput grey pubescent, white setose, median occipital sclerite brown macrosetose; pocl macrosetae absent; postgena sparsely grey pubescent, long, sparsely white setose; clypeus comprised of single sclerite, entirely sclerotized medially, recessed (concave), ventrally simple, posterior to proboscis, laterally connected to face by membranous cuticle; proboscis short, nob-like, occupying approximately ⅓ length of oral cavity, light brown; labellum small, as wide as prementum, as long as prementum, unsclerotized laterally; maxillary palpus laterally compressed (triangular), light brown, approximately ½ length of proboscis.

Antenna: brown; scape white setose dorsally, asetose ventrally; pedicel light brown setose dorsally and ventrally; postpedicel cylindrical in proximal ½, symmetrically bulbous in distal ½, ≥ 2.0 times as long as combined length of scape and pedicel, asetose; apical seta-like sensory element situated apically in cavity on postpedicel.

Thorax: black or light brown to black, predominantly white pubescent; scutum black, light brown stripes medially and laterally, surface macrorugose (distinctly and deeply rugose), predominantly apubescent, paramedian stripes (merging on posterior margin) and lateral margins grey pubescent, scutal setation comprised of long white setae in pubescent areas; dc setae pre- and postsuturally white, acr setae absent, lateral scutal setae white, npl setae 0, spal setae 0, pal setae 0; proepisternum apubescent medially, grey pubescent laterally, long white setose; proepimeron grey pubescent, asetose; antepronotum antero-medially smooth (without any indentation); lateral postpronotum long white setose; postpronotal lobe yellow, white pubescent, long white setose; scutellum grey pubescent, discal scutellar setae absent, apical scutellar setae absent; mesopostnotum grey pubescent, asetose; anatergite grey pubescent, asetose; katatergite apubescent, long white setose, elevated and smoothly convex; anepisternum white pubescent, anteriorly asetose, posteriorly 1-2 white setae postero-ventrally, otherwise asetose; katepisternum white pubescent dorsally, apubescent ventrally, asetose; anepimeron white pubescent, posterior ½ apubescent, asetose; katepimeron white pubescent, asetose; meron white pubescent, median stripe apubescent, asetose; metakatepisternum large; metanepisternum white pubescent, asetose; metepimeron yellow (same color as T1), white pubescent, long white setose, ± flat, infra-halter sclerite absent.

Legs: light brown to brown, setation comprised of white setae and brown macrosetae; pro coxa sparsely grey pubescent, long white setose; mes coxa sparsely grey pubescent, long white setose; met coxa laterally unsclerotized (membrane between coxa and metakatepisternum clearly visible), sparsely grey pubescent, long white setose; met trochanter setose medially; pro + mes femur light brown to brown, met femur light brown to brown, evenly clubbed in distal ¾, macrosetose, 1 antero-ventral and 1 postero-ventral row of macrosetae, postero-ventrally long white, erect setose with setae arranged in distinct row; pro tibia laterally arched; mes tibia laterally arched; met tibia laterally arched, met tibia cylindrical with distinct ventral keel terminating into distinct spur, postero-laterally sparse long white, erect setose with setae arranged in distinct row; pro + mes tarsomere 1 slightly longer than tarsomere 2, met tarsomere 1 slightly longer than tarsomere 2; pulvillus well-developed, as long as well-developed claw, and as wide as the base of the claw; setiform empodium absent.

Wing: length = 7.4 mm; hyaline throughout, veins light brown, microtrichia absent; cells r1, r4, m3, + cua closed, r5 open; C terminating at junction with M1 (or M1+M2); Sc long, terminating in C proximal to r-m; R4 terminates in R1; R5 terminates in R1; auxiliary vein (R3) at base of R4 absent; R4 and R5 widest apart medially; r-m indistinct, R4+5 and M1 fused, forming an X; M1 curves slightly anteriorly at r-m, M1 (or M1+M2) terminates in C; base of M3+M4 present, M3+M4 not terminating together in C (not reaching wing margin), M4 and CuA split proximally to m-cu (cell m3 narrow proximally); CuP straight, cell cup wide, CuP and wing margin further apart proximally than distally; alula well-developed; halter light brown, pubescent, dorsally asetose, ventrally yellow setose.

Abdomen: brown, setation comprised of scattered short white setae, T2-4 parallel-sided and not constricted waist-like, T surface entirely smooth; T1-3 brown with white posterior margin, T4-7 brown; T apubescent; T1 long white setose, T2-7 short white setose; S1-7 light brown; S apubescent; S1-7 sparsely short yellow setose; bullae on T2 transversely elongate, brown, surface entirely smooth, T2 surface anterior to bullae smooth.

♀ abdomen and genitalia: densely arranged anteriorly directed setae present on T7-8 and S7-8; T8 anterior apodeme indiscernible (not dissected), auxiliary spiracle indiscernible (not dissected); T9 formed by wide, rectangular sclerite with median protuberance; T9+10 entirely fused (sclerites indistinguishable), T10 divided into 2 heavily sclerotized acanthophorite plates; 5 acanthophorite spines per plate.

Male. Head: black, in general grey pubescent, light brown, regular, cylindrical setae; width distinctly greater than thorax (at postpronotal lobe), interocular distance on vertex larger than at ventral eye margin; vertex between compound eyes ± horizontally straight, medially only slightly below dorsal eye margin, vertex grey pubescent, white setose; ocellar triangle apubescent; facial gibbosity distinct, well-developed and discernible in lateral view, mystax covering entire facial gibbosity, light brown, white ventrally; parafacial area approximately as wide as ¾ width of central gibbosity (at same level); frons not elevated, medially apubescent, laterally grey pubescent, dark brown; occiput grey pubescent, white setose, median occipital sclerite brown macrosetose; pocl macrosetae absent; postgena sparsely grey pubescent, long, sparsely light brown setose; clypeus comprised of single sclerite, entirely sclerotized medially, recessed (concave), ventrally simple, posterior to proboscis, laterally connected to face by membranous cuticle; proboscis short, nob-like, occupying approximately ⅓ length of oral cavity, brown; labellum small, as wide as prementum, as long as prementum, unsclerotized laterally; maxillary palpus laterally compressed (triangular), brown, approximately ½ length of proboscis.

Antenna: brown; scape white setose dorsally, asetose ventrally; pedicel light brown setose dorsally and ventrally; postpedicel cylindrical in proximal ½, symmetrically bulbous in distal ½, ≥ 3.0 times as long as combined length of scape and pedicel, asetose; apical seta-like sensory element situated apically in cavity on postpedicel.

Thorax: black or brown, predominantly grey pubescent; scutum uniformly black, surface macrorugose (distinctly and deeply rugose), predominantly apubescent, paramedian stripes (merging on posterior margin) and lateral margins grey pubescent, scutal setation comprised of long white to yellow setae in pubescent areas; dc setae pre- and postsuturally white, acr setae absent, lateral scutal setae white, npl setae 0, spal setae 0, pal setae 0; proepisternum apubescent medially, grey pubescent laterally, long white setose; proepimeron grey pubescent, asetose; antepronotum antero-medially smooth (without any indentation); lateral postpronotum long white setose; postpronotal lobe light brown, grey pubescent, long white setose; scutellum grey pubescent, discal scutellar setae absent, apical scutellar setae absent; mesopostnotum grey pubescent, asetose; anatergite grey pubescent, asetose; katatergite apubescent, long white setose, elevated and smoothly convex; anepisternum sparsely grey pubescent, anteriorly asetose, posteriorly asetose, otherwise asetose; katepisternum dorsally sparsely grey pubescent, asetose; anepimeron apubescent, asetose; katepimeron sparsely grey pubescent, asetose; meron apubescent, asetose; metakatepisternum large; metanepisternum grey pubescent, asetose; metepimeron brown (same color as T1), grey pubescent, long white setose, ± flat, infra-halter sclerite absent.

Legs: brown, setation comprised of white setae and brown macrosetae; pro coxa sparsely grey pubescent, long white setose; mes coxa sparsely grey pubescent, long white setose; met coxa laterally unsclerotized (membrane between coxa and metakatepisternum clearly visible), sparsely grey pubescent, long white setose; met trochanter setose medially; pro + mes femur brown, met femur brown, evenly clubbed in distal ¾, macrosetose, 1 antero-ventral and 1 postero-ventral row of macrosetae, postero-ventrally long white, erect setose with setae arranged in distinct row; pro tibia laterally arched; mes tibia laterally arched; met tibia laterally arched, met tibia cylindrical with distinct ventral keel terminating into distinct spur, postero-laterally sparse long white, erect setose with setae arranged in distinct row; pro + mes tarsomere 1 slightly longer than tarsomere 2, met tarsomere 1 slightly longer than tarsomere 2; pulvillus well-developed, as long as well-developed claw, and as wide as the base of the claw; setiform empodium absent.

Wing: length = 6.0 mm; hyaline throughout, veins light brown, microtrichia absent; cells r1, r4, m3, + cua closed, r5 open; C terminating at junction with M1 (or M1+M2); Sc long, terminating in C proximal to r-m; R4 terminates in R1; R5 terminates in R1; auxiliary vein (R3) at base of R4 absent; R4 and R5 widest apart medially; r-m indistinct, R4+5 and M1 fused, forming an X; M1 curves slightly anteriorly at r-m, M1 (or M1+M2) terminates in C; base of M3+M4 present, M3+M4 not terminating together in C (not reaching wing margin), M4 and CuA split proximally to m-cu (cell m3 narrow proximally); CuP straight, cell cup wide, CuP and wing margin further apart proximally than distally; alula well-developed; halter light brown, pubescent, dorsally asetose, ventrally yellow setose.

Abdomen: brown, setation comprised of scattered short white setae, T2-4 parallel-sided and not constricted waist-like, T surface entirely smooth; T1 brown, T2-6 brown with white posterior margin, T7 brown; T sparsely grey pubescent; T1-2 long white setose, T3-7 short white setose; S1-6 light brown, S7 brown; S1-3 apubescent, S4-7 sparsely grey pubescent; S1-7 short white setose; bullae on T2 transversely elongate, light brown, surface entirely smooth, T2 surface anterior to bullae smooth.

♂ abdomen and terminalia: not dissected.

Type locality.

Botswana: Chobe: Kabulabula, Chobe river (17°48'41"S, 024°56'48"E, -17.81139, 24.94667).

Material examined.

Botswana: Chobe: 1♂ Kabulabula, Chobe river , 17°48'41"S, 024°56'48"E, 1930-07-11 - 1930-07-24, Vernay-Lang Kalahari Expedition ( NMSA-DIP-43314 , Holotype, NMSA) ; 1♀ Kabulabula, Chobe river , 17°48'41"S, 024°56'48"E, 1930-07-11 - 1930-07-24, Vernay-Lang Kalahari Expedition ( NMSA-DIP-57787 , Paratype, NMSA) ; Namibia: Ohangwena: 1♂ Oshikango , 17°24'00"S, 015°53'00"E, 1948-07-00, Koch, C. ( NMSA-DIP-43304 , Holotype Lachnocorynus kochi , NMSA) .

Observations at iNaturalist.

Botswana: Ngamiland: 18°57'56"S, 22°56'32"E, 2019-06-10, Taylor, R. (record URL www.inaturalist.org/observations/26760859).

Distribution, biodiversity hotspots, phenology, and biology.

Known only from three localities in northern Botswana and north-central Namibia (Fig. 56 ). A rarely collected species known only from three specimens and two collecting events in 1930 and 1948 and one observation in 2019 (Table 1 ). The species is not known to occur in any currently recognized biodiversity hotspot. Adult flies are active in June-July in mid winter (Table 2 ), which corresponds to the dry season and lower temperatures (data for Kasane, Botswana, see https://worldweather.wmo.int/en/city.html?cityId=1545 and Oshikango, Namibia, see https://www.worldweatheronline.com/oshikango-weather-averages/ohangwena/na.aspx). Nothing is known of the biology.

Remarks.

The male holotype of L. kochi is not well-preserved (Figs 47-49 ) and it cannot in any meaningful way be distinguished from L. chobeensis . The only differences of the male holotypes pertain to the abdominal colouration (T1 and T7 entirely brown in L. chobeensis and all tergites with yellow posterior margins in L. kochi ). The male terminalia were not dissected but are morphologically very similar based on the externally visible structures. These minute differences in colouration cannot be utilized to delineate species and we, therefore, synonymize the two species. Both species were described by Hesse (1969) and he designated L. chobeensis as the type species of the genus. We, therefore, assign L. chobeensis as the senior synonym and this species has also been collected in both the female and male sex during the same collecting event.

Figures

Figure 56. Map of southern Africa with elevational relief and biodiversity hotspots (sensu Conservation International in grey) and distribution of Eremohaplomydas desertorum, Eremohaplomydas gobabebensis sp. nov., Lachnocorynus chobeensis, and Lachnocorynus stenocephalus sp. nov. (SimpleMappr https: // www. simplemappr. net / map / 14089). Distribution and occurrence data available in Google Earth KML file https: // www. simplemappr. net / map / 14089. kml and also through GBIF (data-set https: // www. gbif. org / dataset / 993875 DD- 5915 - 4107 - 8707 - 835 D 5 A 8 D 1022, DOI https: // doi. org / 10.15468 / awpjz 9).

Figures 41 - 46. Lachnocorynus chobeensis: 41 ♂ holotype (NMSA-Dip- 43314, Zenodo https: // doi. org / 10.5281 / zenodo. 6083945), dorsal (https: // doi. org / 10.5281 / zenodo. 6084029) 42 same, lateral (https: // doi. org / 10.5281 / zenodo. 6084031) 43 same, head anterior (https: // doi. org / 10.5281 / zenodo. 6084033) 44 ♀ paratype (NMSA-Dip- 57787, https: // doi. org / 10.5281 / zenodo. 6083949), head anterior (https: // doi. org / 10.5281 / zenodo. 6084045) 45 same, dorsal (https: // doi. org / 10.5281 / zenodo. 6084041) 46 same, lateral (https: // doi. org / 10.5281 / zenodo. 6084043). Scale bars: 5 mm.

Figures 47 - 49. Lachnocorynus chobeensis (♂ holotype of Lachnocorynus kochi, NMSA-Dip- 43304, Zenodo https: // doi. org / 10.5281 / zenodo. 6083947): 47 dorsal (https: // doi. org / 10.5281 / zenodo. 6084035) 48 lateral (https: // doi. org / 10.5281 / zenodo. 6084037) 49 head anterior (https: // doi. org / 10.5281 / zenodo. 6084039). Scale bars: 5 mm.

Figures 53 - 55. Metathoracic coxa in lateral view: 53 Eremohaplomydas gobabebensis sp. nov. (USNMENT 01518012, crop of Fig. 11) 54 Haplomydas crassipes (NMSA-DIP- 77049, crop Fig. 36) 55 Lachnocorynus chobeensis (NMSA-Dip- 43314, crop of Fig. 42).