Centrioncus copelandi, Feijen & Feijen, 2023

Feijen, Hans R. & Feijen, Cobi, 2023, A revision of Centrioncus Speiser (Diptera, Diopsidae, Centrioncinae) with descriptions of new species from Angola, Burundi, and Kenya, ZooKeys 1144, pp. 1-93 : 1

Centrioncus copelandi sp. nov.

Figs 4 , 29 , 74-79 , 80-83 , 84-87 , 88-91 , 92

Type material.

Kenya, holotype, ♂, Coastal Prov., Kasigau Mtn, 3.82700°S, 38.64875°E, 1065 m, 28.xii.2011-11.i.2012, R. Copeland (NMKE). Paratype: 1 ♀, Coastal Prov., Kasigau Mtn, 3.82667°S, 38.64982°E, 1117 m, 30.vi-13.vii.2011, R. Copeland (NMKE).

Diagnosis.

Centrioncus copelandi sp. nov. can be recognised by a mesally slightly depressed, pruinose frons with glossy spots; glossy collar; pruinose blackish brown scutum; dark brown scutellum with brown edges and spines; pleura blackish brown (Figs 74 , 76 ); scutellar spine/scutellum ratio: 0.87-1.00; apical seta/scutellar spine ratio: 0.86-0.92; brown, strongly incrassate fore femur (l/w ratio: ~ 2.65) with ~ 31.7 tubercles, dark brown stripe dorsally on apical third of inner side; very large, distinct central wing spot in distal third of cell br, basal two-fifths of cell r4+5 and distal two-thirds of cell bm+dm (Fig. 4 ); tergites blackish brown; female 7th spiracle in tergite; sternite 4 rectangular; sternite 5 trapezoidal, invaginated anteriorly; sternites 4 and 5 with pair of strongly sclerotised spots; sternite 6 trapezoidal, 1.5 × as broad as sternites 1-5; anterior sclerite of female sternite 7 with w/l ratio: ~ 3.1 (Fig. 81 ); posterior sclerite of female sternite 7 truncated U-shaped, straight anterior and lateral edges with angular anterolateral corners; female cercus elongate, l/w ratio: ~ 4.4; subanal plate pentagonal, apically tapering into short extension; spermathecae rounded, basally flat (Fig. 85 ), with small apical dimple; spermathecal ducts with constriction near spermathecae; outer and median arms of surstylus well separated, with short broad common base; outer arm constricted at base, apically broadening to 3 × width of base, sides concave, with 16 apical tubercles (Fig. 88 ); median arm a slender rod, apically some long setulae but no spinous setae, slightly shorter than outer arm; inner arm twice as broad as median arm and slightly longer, apically with shape of cap opener; subepandrial clasper elongate, basal third constricted, apical corners angular, apically strongly convex; cercus (Fig. 89 ) with broad lateral extension on distal third, apically convex.

Description.

Measurements. Body length ♀ 5.1 mm, ♂ 5.0 mm, width of head ♀ 1.08 mm, ♂ 1.13 mm, wing length ♀ 4.3 mm, ♂ 4.3 mm, length of scutellar spine ♀ 0.34 mm, ♂ 0.31 mm.

Head. Frons slightly depressed mesally, brown but mesally and anteriorly paler brown, black stripe posterior to FOS; frons pruinose, anterolaterally more densely pruinose, black stripe behind FOS glossy, small glossy spots lateral to ocellar tubercle (Fig. 75 ); occiput blackish brown, with lateroventral corners yellowish brown (Fig. 76 ), uniformly pruinose, more densely pruinose dorsomesally; face yellowish brown, pruinose, denser pruinosity along eye margins; antenna yellowish brown, funiculus with dark spot at base of arista; maxillary palpus dark; OVS 0.31 mm in ♀ and 0.29 in ♂, FOS 0.24 mm in ♀ and ♂.

Thorax. Collar glossy dark brown; scutum blackish brown, pruinose, posterior half of humeral callus glossy (Fig. 76 ); scutellum dark brown, pruinose, posterior and lateral edges and scutellar spines yellowish brown (Figs 74 , 76 ); pleura dark brown, pleura mainly pruinose, glossy sections include anterior proepisternum, ventral edge of anepisternum, ventral half of katepisternum and ventral spot on anepimeron, densely pruinose spots on posterior section of anepimeron and dorsoposterior section of katepisternum (Figs 74 , 76 ); posterior notopleural, supra-alar and infra-alar setae present, infra-alar seta twice as long as posterior notopleural and supra-alar setae, supra-alar seta on inconspicuous carina (Fig. 74 ); basiliform prosternum lanceolate and anteriorly sharply pointed and with line-like extension; scutal length/scutal width ratio: 1.1; scutellum projecting at angle of just> 20° from body axis; scutellar spines almost aligned with dorsal plane of scutellum, diverging at angle of ~ 50°; scutellar spine/scutellum ratio: 1.00 in ♀ and 0.87 in ♂; scutellar spine/length of body ratio: 0.067 in ♀ and 0.063 in ♂; apical seta/scutellar spine ratio: 0.86 in ♀ and 0.92 in ♂; scutellar length/scutellar width (at base) ratio: ~ 0.70.

Wing. Almost transparent with very large, distinct, brownish central spot in distal third of cell br, basal two-fifths of cell r4+5, distal two-thirds of cell bm+dm and slightly extending into cells r2+3, m1 and m4 (Fig. 4 ); glabrous basal areas only include cells bc and c and small basal and subbasal spots in cell br; crossvein h distinct; cell sc closed; vein CuA+CuP from vein CuP onward extending under angle of 25° to wing margin in almost straight line (Fig. 4 ); cell cua triangular; vein M4 continuing distal of crossvein dm-m in almost straight line to wing margin; alula distinct; crossvein bm-m very vaguely indicated.

Legs. Coxa 1 and trochanter 1 whitish (Fig. 76 ), thinly pruinose; femur 1 glossy, yellowish brown with dark brown stripe on apical third of dorsal part of inner side (Figs 74 , 78 ); tibia 1 dark brown, pruinose; metatarsus 1 yellowish brown, other tarsal segments whitish; mid and hind legs pale yellowish brown; apex of femur 2 brown; femur 3 dark brown on apical seventh (Fig. 74 ); tibia 3 with brown spots basally and apically (Fig. 74 ); femur 1 strongly incrassate in ♀ and ♂ (Figs 74 , 78 ), l/w ratio: 2.62 in ♀ (n = 1) and 2.67 in ♂ (n = 1), inner row of spinous setae (Fig. 78 ) with 4-5 setae (n = 3), outer row with 4 setae (n = 3), inner row of tubercles with 15.3 tubercles (range 15-16, n = 3), outer row with 16.3 tubercles (range 15-17, n = 3); femur 3 (Fig. 79 ) with 5.0 tubercles (range 4-6, n = 3); setal formula 4.0, 4.7, 16.3, 15.3, 5.0; femora 2 and 3 without apical spurs.

Preabdomen. Tergites blackish brown (Fig. 77 ), very thinly pruinose, posterior edges of tergites 2 and 3 with more densely pruinose band; sternites dark brown; lateral edges of membranous ventral areas with dark brown spots; sternite 1 rectangular, constricted mesally (Fig. 80 ); intersternite 1-2 very dark, laterally acuminate, with thin lateral connections to main sternite 2; sternite 2 rectangular, posterior of intersternite with small membranous area; sternite 3 rectangular with two narrow, elongate, more sclerotised areas (Fig. 80 ); sternite 4 rectangular with convex lateral sides and two distinct, heavily sclerotised spots anteriorly; sternite 5 trapezoidal, anteriorly strongly constricted mesally, with two distinct, heavily sclerotised spots anteriorly (Fig. 80 ); sternite 6 trapezoidal, ~ 1.5 × as broad as sternites 1-5; sternites 1-3 glossy, sternites 1 and 3 with a few microtrichia laterally; sternites 4-6 pruinose; 1st spiracle in membrane.

Female postabdomen. Tergite 7 brown, with mesal gap posteriorly, posterior gap extending to lateral sides, lateral edges curved under ventrally; suture in basal ring of segment 7 faint; 7th spiracle well into tergite (Fig. 82 ); anterior sclerite of sternite 7 rectangular, slightly tapering posteriorly (Figs 81 , 82 ), w/l ratio: ~ 3.1 (Table 8 ), dark brown, glossy on basal third, pruinose posteriorly (Figs 81 , 82 ), with ~ 30 setulae; posterior sclerite of sternite 7 truncated U-shaped, consisting of broad anterior section and two broad lateral extensions (Figs 81 , 82 ), anterior edge straight and parallel to posterior edge of anterior sternite, lateral edges of extensions straight and diverging posteriorly, anterolateral corners angular, posterolateral apices rounded, clothed in microtrichia and with four setulae at posterior apices; tergite 8 consisting of two oblong plates, well separated mesally (Fig. 83 ); sternite 8 consisting of two oblong plates; tergite 10 (Fig. 83 ) onion-shaped, extending posteriorly between cerci, clothed in microtrichia, with one pair of strong setulae; cercus elongate, somewhat tapering posteriorly (Fig. 83 , Table 8 ), l/w ratio: ~ 4.4; subanal plate (Figs 83 , 84 ) somewhat pentagonal, laterally rounded and apically tapering into short extension, clothed in microtrichia except anterior edge, with ~ 26 setulae; spermathecae heavily sclerotised, smooth, rounded, basally flattened (Fig. 85 ), with small apical dimple; junction of ducts of paired spermathecae V-shaped, spermathecal duct with distinct constrictions near junction with spermathecae (Fig. 85 ).

Male postabdomen. Tergite 6, sternite 8 and epandrium uniformly blackish brown; epandrium broad and rounded (too damaged to measure w/l ratio), clothed in microtrichia; outer and median arms of surstylus well separated, with short broad common base (Fig. 88 ); outer arm deeply constricted at base with concave lateral sides, broadening apically to ~ 3 × basal width, apically with row of 16 tubercles, basally with nine setulae (2 very long) on inner side and a few small setulae along apical edge, on outer side with a few small setulae and central patch of microtrichia; median arm (Fig. 88 ) slender, parallel-sided, rod-shaped, almost as long as outer arm, apically with four small setulae and two long setulae, no spinous setae present; inner arm twice as broad as median arm and slightly longer, apical quarter abruptly narrowed, cap opener-shaped, apically with seven setulae; subepandrial clasper (Fig. 90 ) somewhat elongate, basal third constricted, apical corners angular, apically strongly convex, glabrous, with four long setulae on inner side; cercus (Fig. 89 , Table 8 ) slender, with broad lateral extension on distal third, apically convex, clothed in microtrichia and short setulae, 7 longer setulae along apical edge, length/greatest width ratio: 1.5 (Table 8 ); ejaculatory apodeme + sac (Fig. 91 , Table 9 ) very large, 10.1% of body length, ejaculatory apodeme slender, apically broadening.

Egg. Female with two damaged full-grown eggs and some pieces of undeveloped eggs in abdomen. Eggs (Fig. 86 ) measured 1.01 mm in length with elevated longitudinal ridges spanning from anterior pole to posterior pole with fine, roughly hexagonal microstructures between ridges (Fig. 87 ).

Distribution and habitat.

The localities of the type series are indicated on the map for Eastern Africa (Fig. 29 ). The collecting sites varied from 1056 to 1117 m in altitude. The habitat of the Kasigau site at 1117 m is shown in Fig. 92 . The distribution appears to be limited to the Kasigau Massif of the Taita Hills (see also under C. bytebieri ). Centrioncus bytebieri is only known from the Dabida Massif of the Taita hills. The gravid female was collected in early July, in the middle of the dry season which is unusual for Centrioncus flies.

Etymology.

The specific epithet of C. copelandi sp. nov. refers to the name of its collector Dr Robert S. Copeland (ICIPE), who contributed a significant number of Centrioncus specimens to this study.

Remarks.

From the shape of the outer arm of the surstylus (apically much wider than at base, with large number of 16 or 17 tubercles), absence of spinous setae on the median arm of the surstylus, the very large central wing spot and anteriorly strongly constricted sternite 5, it can be postulated that the closest known relative of C. copelandi sp. nov. is C. prodiopsis . From a geographical point of view that also makes some sense (Fig. 29 ), although C. bytebieri occurs closer to C. copelandi sp. nov.

Figures

Figure 29. Distribution map of the seven Eastern African Centrioncus species.

Figure 92. Centrioncus copelandi sp. nov., Kenya, Kasigau Mtn, collection site at 1117 m. Photograph by Robert Copeland.

Figures 1 - 4. Centrioncus, dorsal view of wings 1 ♂, C. aberrans, Timboroa Forest 2 ♀, paratype, C. bururiensis sp. nov., Bururi Nat. Forest 3 ♂ C. bytebieri, Ngangao Forest 4 ♀, paratype, C. copelandi sp. nov., Kasigau Mtn. Scale bars: 0.5 mm.

Figures 74 - 79. Centrioncus copelandi sp. nov., Kasigau Mtn 74 ♂, holotype, lateral view (abdomen removed) 75 - 79 ♀, paratype 75 head, frontal view 76 head posterolateral view, thorax, lateral view 77 abdomen, dorsal view 78 fore femur, ventral view 79 hind femur, ventral view. Scale bars: 0.5 mm.

Figures 80 - 83. Centrioncus copelandi sp. nov., ♀, paratype, Kasigau Mtn 80 sternites 1 - 6, ventral view 81, 82 sternite 7, ventral view 83 terga 8, 10 and cerci, dorsal view. Scale bars: 0.2 mm

Figures 84 - 87. Centrioncus copelandi sp. nov., ♀, paratype, Kasigau Mtn 84 subanal plate, ventral view 85 spermathecae 86 egg 87 egg, detail of external microstructure. Scale bars: 0.1 mm (84, 85, 87); 0.2 mm (86).

Figures 88 - 91. Centrioncus copelandi sp. nov., ♂, holotype, Kasigau Mtn 88 surstylus, inner view 89 cercus, posterior view 90 subepandrial clasper, posterior view 91 ejaculatory apodeme + sac. Scale bars: 0.1 mm.