Skusella pallidipes
Creators: name: Cranston, Peter S.
name: Tang, Hongqu
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Chironomidae
Skusella
Skusella pallidipes

description: Skusella pallidipes (Kieffer, 1921)
(Figs 1B, G, I–J; 3D; 4I, 5B)
Lauterborniella pallidipes Kieffer 1921: 52; Freeman 1958: 323.
Skusella pallidipes (Kieffer), Freeman 1961: 718, short note.
Material examined. 1♂, SUDAN [SOUTH SUDAN], Wupatong, nr Wau, 19.iii.1955 (Reid) BM1955-382 (NHM); 1♂ nr. Wau (Schorch) (NHM), 1♂, BELGIAN CONGO, Elisabethville [DR CONGO, Lubumbashi], iii.1939 (Brédo)(NHM); 1♂, 1♀, IVORY COAST, no further data (Dejoux) (ZSM); 1♀, NIGERIA, Anambra State, Opi Lake 1 (= Ogelube Lake), 6°45'0"N 7°29'30"E, 4–5.xi.1978, emergence trap (Hare)(NHM); 1 Pe (putative identity), same except 28.i.–7.ii.1978.
Material mapped, not examined. Sudan [South Sudan]: Melut, Adok, Shambe; Nigeria: Katsina, Kankiya; Sierra Leone: Pepel; Gold Coast [Ghana]: Nangodi; French Cameroons [Cameroon]: Kribi; Belgian Congo [DR Congo]: Musosa; S. Rhodesia [Zimbabwe]: Salisbury [Harare].
Description. Adult male (n = 5). B.l. 6.0– 6.8 mm, W.l. 2.4–2.7. Antenna: Fl1–12 405–445, Fl13 1115–1240, A.R. 2.75–2.92. 19–14 temporals, 17–23 clypeals. Palps (2–5): 65–75, 145–180, 190–210, 300–370. Thoracic contour double humped; L. aps 4–5; ac 0, dc 9–13, pa 2–3, Scts 6–8. Vein setal counts R 7–11, R 1 16–17, R4+ 5 17–22, VR 1.08–1.14.
Wing patterned as in Fig. 1B (female). Vein setal counts R 16, R 1 16–17, R4+ 5 11–16. V.R. 1.18. V.R. 1.07–1.14. Squama bare.
Legs: Fore-tibial scale large without spur, mid and hind tibial combs nearly fused, bearing 1 hooked spur. LR1 1.65–1.80, LR2 0.39–0.44, LR3 0.68–0.74; BV1 1.50–1.64, BV2 3.30–3.50; BV3 2.65–2.80. SV1 1.41–1.54, SV2 4.60–4.90, SV3 2.88–3.00.
Hypopygium (Fig 1G, 1I –J). Bands of tergite IX very faint, nearly meeting, lacking median setae, lateral to anal point TIX has several fine long seta. Superior volsella (Fig. 1I) tapering to dorsally curved apex, with 2 long inner setae arising from large basal tubercles. Median volsella 50µm, thin stemmed, with simple setae and taeniae (Fig. IJ). Gcx 240–300, Gst 165–202; H.R. 3.05–3.86.
Adult female (n = 3, all under- or over-cleared; 1 slide label states ‘dried out’).
Body length c. 3.5–3.6 mm. Wing length 1.8–1.9 mm.
Head 9–10 temporals, 14–15 clypeals. Antenna 110–130, 65–70, 70, 60, 150, AR 0.41–0.42. Palp lengths (2– 5): 40, 210–220, 220, 310–315.
Thorax. With double scutal hump, anterior larger than longer, shallower posterior. Setation: 1 L. aps, 9–10 dc, 3 pa, 3–5 scts.
Wing (Fig. 1B). Pattern similar to but fainter than male and figure (perhaps all “bleached): with two broad separate darker bands each extending full width of wing. Vein setal counts R 23–28, R 1 21–28, R4+5 33–46. V.R. 1.18.
All legs damaged, all tarsomeres absent: pale, at most faintly darker at femoral-tibial junction.
Genitalia. Similar to S. subvittata except coxosternapodeme IX thicker, darker and more sinuous; seminal ducts more sinuous / recurved, ending very close, perhaps fused in single opening. Seminal vesicles elongate-ovoid 105–120 long, maximum width 50–60, with strong neck before recurved ducts (Fig. 3D). Notum 200 long (fused section 125–150). Gonocoxite IX small, with 3–4 long setae. Dorsomesal lobe with scattered microtrichia and mesal scales. Cerci 75 long by 45–50 wide. Tergite IX heavily setose, undivided.
Pupa (n = 1, putative). 5.6 mm long. Exuviae mid-brown with darker apophyses.
Cephalothorax. Cephalic area weakly creased with well developed cephalic tubercles but lacking frontal setae. Prominent scale-covered scutal hump at anterior 1/4. Prealar tubercle rounded. Base of thoracic horn oval, tracheal bundle densely packed, 35 x 17 µm.
Abdomen (Fig. 5B). Tergites II–VI with more extensive spinules, on II–V broad anteriorly, narrowed in midsection and posteriorly broader between apophyses; TVII–VIII with dense small spinules in anterior 1/3. Pleurae without spinules. Tergite II with row of 23 hooks extending 20% of tergite width. Vortex absent. Pleural fringe only on segment VIII. Posterolateral ‘comb’ on VIII with 11 teeth in two discrete sizes (larger lateral, smaller medial) (Fig. 4H).
Larva. Unknown/unassociated, but see Comments below and Skusella sp. ‘Opi’.
Comments. Material from Lake Opi, Nigeria collected by Landis Hare comprises 5 slides. Although all specimens belong to Skusella, the only slide (and its’ label) that shows an association is a pupal exuviae with emerged female conforming to S. freemani Harrison (see below). A second female from an emergence trap with a clearly visible bare squama, plain legs and characteristic seminal ducts conforms to S. pallidipes. The presence of two species is confirmed by two differing pupal exuviae. One has a pleural fringe extending from the posterior of segment III to VIII and is associated by rearing with the adult female identified as S. freemani. The other, an unassociated pupal exuviae from a mass rearing, has a pleural fringe restricted to segment VIII: it is treated here as belonging to S. pallidipes. Larvae cannot be allocated with certainty to either species and are treated below as Skusella sp. ‘Opi’. It is unfortunate that in the 40 years since Hare’s pioneering work in West Africa there have been few further regional studies to reveal new life history associations.
description: Published as part of Cranston, Peter S. & Tang, Hongqu, 2018, Skusella Freeman (Diptera: Chironomidae): new species, immature stages from Africa, Asia and Australia, and expanded distributions, pp. 41-65 in Zootaxa 4450 (1) on pages 50-51, DOI: 10.11646/zootaxa.4450.1.3, http://zenodo.org/record/1444592