Campsicnemus scurra Parent

Evenhuis, Neal L., 2009, Review of Campsicnemus (Diptera: Dolichopodidae) of the Marquesas, French Polynesia, with description of four new species groups, Zootaxa 2004, pp. 25-48 : 31-32

Campsicnemus scurra Parent

( Figs. 5 , 8 )

Campsicnemus scurra Parent, 1934: 299 . Bickel & Dyte, 1989: 412; Evenhuis, 2000: 290, 2004: 41 (fig. 11); Yang et al., 2006: 467.

Diagnosis. This species is easily distinguished from the other species in the gladiator group by the mid and hind femora possessing long setae and cilia on their apical halves; and IIt1 possessing a single strong apical spur.

Redescription. Male. Body length: 2.11–2.45 mm. Wing length: 2.44–2.69 mm.

Head. Black, face dark brown to black with reddish highlights, paler brown near clypeus; oc and vt black, about one-third length of antennal arista; front, occiput, and vertex black with blue highlights; face constricted at middle, almost holoptic, eyes separated below antennae by width of 1–2 ommatidia; palp small, dark brown; proboscis brown, extending below eye in lateral view; antennal segments black to brown; postpedicel long, lanceolate, length about 3.5 x width; arista slightly longer than head height.

Thorax: Mesoscutum, scutellum, and pleura dark brown to black throughout, with a few metallic greenish highlights laterally; thoracic setae black: 1 + 3 dc; 2 np; 2 ph; 1 pa; 1 + 1 sc; ac absent; halter stem white, knob dark brownish black.

Legs: CI yellowish white, with apical tuft of three strong black setae, approximate basally, almost fused apically so as to appear as a single strong seta; CII and CIII brown, slightly paler than surrounding pleura; FI and FII yellowish brown, FIII yellowish brown basally, becoming darker brown on apical one-fourth; remainder of legs brown; FI and remainder of foreleg unmodified, without MSSC; FII slightly bowed with strong chetae basally, setae thinner toward apex, with subapical brown patch (sensory area?) harboring two small setae; FIII slightly bowed with swollen basal area containing 3–4 medium sized black setae and two long setae more apically, middle of FIII not swollen, containing very long curved, sinuous, and wrinkled setae on ventral surface (MSSC); TiII slightly bowed and swollen medially, with long setae in middle on dorsal surface (MSSC), smaller black setae and hairs along entire ventral surface. TiIII with long hairs basoventrally, dorsal surface with small hairs and only two long setae (one subbasally; the other near middle) (MSSC). IIt1 short, about one-half length of IIt2, with single strong black, blunt apical seta (MSSC). Remainder of leg segments without MSSC.

Wing: pale smoky throughout.

Abdomen. Dark brown with short black hairs dorsally on each tergite, a few longer hairs laterally; tergal interstices whitish; sternites yellowish brown. Hypopygium brown with paler brown cerci, not dissected.

Female. As in male except for lack of MSSC; postpedicel length about 1.5 x width; legs normal, without modifications; FI and FII brown.

Material examined. FRENCH POLYNESIA: Marquesas Is: NUKU HIVA: 2 Ψ, middle Hakaui Valley, 300 ft [91 m], on small pool of streamlet tributary to upper midreach, 8°54'46"S, 140°09'52"W, 19 Oct 1999, R. Englund ( BPBM); 10 ɗ, 2 Ψ, same data except D.A. Polhemus ( BPBM, USNM); 2ɗ, 3Ψ, tributary to upper Taipivai River, 1600 ft [488 m], water temp. 21.5 °C, 8°52'53"S, 140°07'03"W, on pools, 22 Oct 1999, D.A. Polhemus ( BPBM, USNM); 1ɗ, 8Ψ, Taipi Valley, Tehua Falls, 500 ft [152 m], water temp. 23 °C, 8°52'14"S, 140°06'16"W, above rocks in rapids, 18 Oct 1999, D.A. Polhemus ( BPBM, USNM); 2ɗ, streamlet crossing road above Taiohae, 1250 ft, water temp. 23 °C, 8°53'21"S, 140°06'25"W, skating on pools, 18 Oct 1999, D.A. Polhemus ( USNM); 5ɗ, 2Ψ, Haaotupa Bay Stream, 8.9194°S, 140.1178°W, 17 Oct 2000, D.A. & R.E.G. Craig ( BPBM); 9ɗ, 5Ψ, Taipi, 500 ft [152 m], 22 Aug 2001, R. Englund ( BPBM); 6ɗ, 3Ψ, Stream on S. side Tekau Ridge, 2700 ft [823 m], 25 Aug 2001, R. Englund ( BPBM). [Type in MNHN not examined.]

Discussion. This water skater is found in many parts of the southern portion of the island of Nuku Hiva on pools associated with a wide variety of streams and at various elevations from ca. 90–490 m [300–1600 ft].

Evelyn Cheesman collected this species, which Parent (1934) described. The species is only known from a single male and the data given by Parent “Marquesas Is. Nuka-hiva. St. Georges Exp. L.E. Cheesman (B.M.)” gives no indication of the specific locality on the island where it was captured nor on what date it was collected. The list of Diptera from French Polynesia collected during this expedition published by Aubertin & Cheesman (1929), gives no specific locality data for any of the species collected on Marquesan Islands during that expedition. However, Cheesman (1932) helps somewhat by giving a detailed account of her travels on Nuku Hiva during the St. George Expedition.

The St. George, a 191-foot three-masted barquentine yacht of 694 tons gross, initially landed at the southeastern port of Taipivai on Nuku Hiva in the latter half of January 1925 and stayed only a short time in order to sail on to Hakaui, a port further west on the island. Cheesman was primarily interested in seeing the “desert” region of the western portion of the island (labeled as “Le Desert” on maps of the islands she had seen), but decided to debark at Taipi[vai] to collect. She hiked up Taipivai Valley the first day and, instead of returning to the ship, decided to hike from Taipivai to Hakaui (a 9-hour hike) to arrive a day before the ship was due to arrive. After her day-long hike and reconnoitering with the St. George, she hiked the next day up the Hakaui Valley and climbed the cliffs on its west side (about a 1600-foot climb) in order to finally see the “desert” region, only to be disappointed. It was not a desert at all, but grassy plain that she said was “without anything that would attract insects”.

From her 1932 account, she only mentioned collecting insects in pools and small creeks while hiking along the knife-edged ridge above Hakaui. It is thus possible to delimit the capture of the type specimen of Campsicnemus scurra to most probably the pools or creeks in the area near the Hakaui River (see Fig. 8 ) from 23–25 January 1925 [the St. George left Hakaui on 25 January after a three-day anchorage there ( Douglas & Johnson 1926)].

Figures

FIGURES 3 – 6. Campsicnemus gladiator group, male mid basitarsi. 3. C. gladiator, n. sp. 4. C. limnobates Evenhuis. 5. C. scurra Parent. 6. C. uncleremus Evenhuis.

FIGURES 7 – 9. Marquesan habitats. 7. Hiva Oa, Upper Atuona Valley, Atikoua Stream: type locality for Campsicnemus plautus, n. sp. and habitat for C. uncleremus Evenhuis. Collector Dan Polhemus in foreground. 8. Nuku Hiva, Hakaui River: probable type locality for C. scurra Parent. 9. Ua Huka, Hitikau Ridge. Inset: collector Dan Polhemus fogging on ridge summit: habitat for C. uu, n. sp.