Centrioncus crassifemur, 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

publication ID	https://dx.doi.org/10.3897/zookeys.1144.95619
publication LSID	lsid:zoobank.org:pub:565B46A4-C01B-4542-9635-6F3ED6472747
persistent identifier	https://treatment.plazi.org/id/C2531274-139D-4B06-8662-F44C89C8D602
taxon LSID	lsid:zoobank.org:act:C2531274-139D-4B06-8662-F44C89C8D602
treatment provided by	ZooKeys by Pensoft
scientific name	Centrioncus crassifemur
status	sp. nov.

Treatment

Centrioncus crassifemur View in CoL sp. nov.

Figs 5 View Figures 5–8 , 93-96 View Figures 93–96 , 97-100 View Figures 97–100 , 101-105 View Figures 101–105 , 106-109 View Figures 106–109

Type material.

Angola, holotype, ♀, Salazar I.I.A.A. N’dalatando (Salazar) [most probably Instituto de Investigação Agronomica de Angola at Quilombo, 5 km to north of N’dalatando, 8°53'1"S, 14°44'59"E, 600-> 1000 m], 9-15.iii.1972, Southern African Exp. B.M. 1972, no collector given [probably leg. P.M. Hammond] (NHMUK).

Diagnosis.

Centrioncus crassifemur sp. nov. can be recognised by the mesally slightly depressed, pruinose frons; mainly pruinose collar; pruinose blackish brown scutum with brownish humeral calli; dark brown, pruinose scutellum with pale scutellar spines; pleura blackish brown with anterodorsal corner of anepisternum brown (Fig. 93 View Figures 93–96 ); scutellar spine/scutellum ratio: 0.81; apical seta/scutellar spine ratio: 0.81; fore femur (Figs 93 View Figures 93–96 , 98 View Figures 97–100 ) strongly incrassate (l/w ratio: 2.36) with ~ 41.5 tubercles, pale brown, on distal third dark brown on both sides; distinct central brownish wing spot around crossvein r-m in distal tip of cell br and basal fifth of cell r4+5, somewhat extending into cell bm+dm (Fig. 5 View Figures 5–8 ); tergites dark brown, posterolateral corners of tergites 2-4 paler brown; female 7th spiracle just in tergite; sternite 4 rectangular; sternite 5 square; sternite 6 trapezoidal, 1.5 × as wide as sternites 1-5; anterior sclerite of female sternite 7 broad, very short (w/l ratio: ~ 8.6); posterior sclerite of female sternite 7 large, membranous, trapezoidal plate, two tiny more sclerotised sections in anterolateral corners (Figs 102 View Figures 101–105 , 104 View Figures 101–105 ); female cercus elongate, l/w ratio: 4.3; subanal plate (Fig. 105 View Figures 101–105 ) laterally rounded, pentagonal, apically pointed; spermathecae round in cross section, flattened with large apical dimple and central pinnacle (Figs 106 View Figures 106–109 , 107 View Figures 106–109 ).

Description.

Measurements. Body length ♀ 5.1 mm, width of head ♀ 1.23 mm, wing length ♀ 4.5 mm, length of scutellar spine ♀ 0.31 mm.

Head. Frons slightly depressed mesally, dark brown, with lateral margins pale brown, mainly pruinose except glossy areas lateral to ocellar tubercle (Figs 95 View Figures 93–96 , 96 View Figures 93–96 ); occiput glossy brown with some pruinescence posteriorly to ocellar tubercle and densely pruinose margins near eyes; face yellowish brown, thinly pruinose, with denser pruinosity along eye margins (Fig. 95 View Figures 93–96 ); antenna yellowish brown, dorsal section of funiculus and basal segments of arista darker (Figs 95 View Figures 93–96 , 96 View Figures 93–96 ); maxillary palpus dark; outer vertical seta 0.30 mm, fronto-orbital seta 0.18 mm.

Thorax. Collar dark brown, mainly pruinose, mesally and anteriorly glossy (Fig. 96 View Figures 93–96 ); scutum blackish brown and pruinose, humeral callus brown and more glossy (Figs 93 View Figures 93–96 , 96 View Figures 93–96 ); scutellum dark brown, pruinose; scutellar spines pale, but narrowly brownish basally (Figs 93 View Figures 93–96 , 96 View Figures 93–96 ); pleura dark brown with only anterodorsal corner of anepisternum paler brown; pleura mainly thinly pruinose, densely pruinose areas around and below anterior spiracle, anterior and posterior sections of anepisternum, and dorsal anterior and posterior sections of katepisternum, glossy sections include ventral edge of anepisternum and ventral half of katepisternum (Fig. 93 View Figures 93–96 ); posterior notopleural seta, supra-alar and infra-alar setae present, supra-alar seta ca. two-thirds length of other two setae; basiliform prosternum lanceolate and sharply pointed anteriorly (Fig. 94 View Figures 93–96 ); scutal length/scutal width ratio: 1.22 (Fig. 96 View Figures 93–96 ); scutellum projecting at angle of ~ 20° from body axis; scutellar spines almost aligned with dorsal plane of scutellum (Fig. 93 View Figures 93–96 ), diverging at angle of just> 30°; scutellar spine/scutellum ratio: 0.81; scutellar spine/length of body ratio: 0.06; apical seta/scutellar spine ratio: 0.81; scutellar length/scutellar width (at base) ratio: 0.74.

Wing. Almost transparent but slightly tinged; distinct central brownish spot around crossvein r-m in distal tip of cell br and basal fifth of cell r4+5, somewhat extending into cell bm+dm (Fig. 5 View Figures 5–8 ); some infuscation around vein M4 proximal to crossvein dm-m; glabrous basal areas only include cells bc and c and basal third of 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; vein M4 continuing distal of crossvein dm-m in almost straight line towards wing margin; cell cua subtriangular; alula distinct; crossvein bm-m vaguely indicated.

Legs. Fore coxa and trochanter yellowish white, thinly pruinose; fore femur glossy, pale brown with darker brown apex (Figs 93 View Figures 93–96 , 97-99 View Figures 97–100 ); fore tibia glossy brown with paler, more pruinose base; fore metatarsus yellowish brown, other tarsal segments whitish (Fig. 93 View Figures 93–96 ); mid and hind legs pale yellowish brown, apical quarter of hind femur brown (Fig. 100 View Figures 97–100 ); fore femur strongly incrassate in ♀ (Figs 97-99 View Figures 97–100 ), l/w ratio: 2.36 (n = 1), fore femur subbasally connected to trochanter (Fig. 98 View Figures 97–100 ) on inner side [assumed adaptation to very incrassate femora], inner row of spinous setae (Fig. 98 View Figures 97–100 ) with five setae, outer row with four setae, inner row of tubercles with 20-21 tubercles, outer row with 21 tubercles; hind femora with six and nine (Fig. 100 View Figures 97–100 ) tubercles; setal formula 4.0, 5.0, 21.0, 20.5, 7.5; no apical spurs on mid and hind femora.

Preabdomen. Dark brown, thinly pruinose, posterolateral corners of tergites 2-4 paler brown, posterior half of tergite 7 pale brown (Fig. 93 View Figures 93–96 ); sternites 1-6 brown, sternites 1 and 2 glossy, sternites 3-6 pruinose; sternite 1 slightly trapezoidal (Fig. 101 View Figures 101–105 ); sternite 2 anteriorly with very slender, more sclerotised section mesally with two minute setulae laterally; sternites 2-4 all rectangular, slender, more or less equal in width; sternite 5 square; sternite 6 (Fig. 102 View Figures 101–105 ) trapezoidal, ~ 1.5 × as wide as sternites 1-5; 1st spiracle in membrane.

Female postabdomen. Tergite 7 (Fig. 104 View Figures 101–105 ) with large mesal gap posteriorly, lateral edges only marginally curved under ventrally; suture in basal ring of segment 7 hardly visible; 7th spiracle at edge of tergite (Fig. 104 View Figures 101–105 ); anterior sclerite of sternite 7 rectangular, broad and very short, w/l ratio: ~ 8.6, covered with microtrichia and some setulae on posterior half (Fig. 104 View Figures 101–105 , Table 8 View Table 8 ); posterior sclerite of sternite 7 trapezoidal plate, weakly sclerotised with two very small more sclerotised sections in anterolateral corners (Fig. 104 View Figures 101–105 ), covered with microtrichia and with ~ 10 setulae posteriorly; tergite 8 consisting of two oblong plates, narrowly separated mesally, central sections more sclerotised (Fig. 103 View Figures 101–105 ); sternite 8 consisting of two oblong plates, expanding posteriorly, and posteriorly linked mesally (Fig. 102 View Figures 101–105 ); tergite 10 (Fig. 103 View Figures 101–105 ) somewhat onion-shaped, extending posteriorly between cerci, laterally bare, otherwise clothed in microtrichia and with two pairs of setulae; cercus elongate, l/w ratio: 4.3 (Table 8 View Table 8 ); subanal plate (Figs 102 View Figures 101–105 , 105 View Figures 101–105 ) laterally rounded, apically pointed, subpentagonal, ventrally covered with microtrichia and> 20 setulae on apical half; spermathecae heavily sclerotised, smooth, round in cross section, flattened with large apical dimple and peculiar central pinnacle (Figs 106 View Figures 106–109 , 107 View Figures 106–109 ); junction of ducts of paired spermathecae V-shaped (Figs 106 View Figures 106–109 , 107 View Figures 106–109 ).

Egg. Holotype with six almost fully developed eggs in abdomen. Eggs (Figs 108 View Figures 106–109 , 109 View Figures 106–109 ) measured 0.9 mm in length, with longitudinal ridges spanning from anterior pole to posterior pole with fine, nearly hexagonal, microstructures on and in between ridges. With different illumination settings, either ridges become more distinct (Fig. 109 View Figures 106–109 ) or hexagonal microstructures (Fig. 108 View Figures 106–109 ).

Distribution and habitat.

The single known specimen is from north-western Angola. The holotype was most likely collected in rain forest around the experimental station of the Instituto de Investigação Agronomica de Angola at Quilombo. The altitude of the collecting locality must then have been between 600 and slightly> 1000 m. The gravid holotype was collected in early March, which falls in the second half of the rainy season in Angola.

Etymology.

The specific epithet of C. crassifemur sp. nov. refers to the remarkably incrassate fore femora.

Remarks.

The more sclerotised anterior margin of sternite 2 forms an integral part of sternite 2 (Fig. 101 View Figures 101–105 ) and is not, like in other Centrioncus , with thin lateral connections tied to the main region of sternite 2. Given the shape of the posterior sclerites of female sternite 7, the closest known relative of C. crassifemur sp. nov. could be C. aberrans . However, it is possible that the shape of sternite 7 simply represents a symplesiomorphic condition. Centrioncus aberrans and C. bururiensis sp. nov. are geographically speaking its closest known relatives.