Campsicnemus rheocrenus Evenhuis

Evenhuis, Neal L., 2008, The Campsicnemus lobatus and zigzag groups in the Society Islands, French Polynesia (Diptera: Dolichopodidae), Zootaxa 1910, pp. 27-44 : 35-36

Campsicnemus rheocrenus Evenhuis , new species

( Fig. 6 , 13 )

Diagnosis. Among species of the lobatus group, it is similar to C. lobatus but can be separated from it by the lack of a falcate wing tip (present in C. lobatus ) and, if present, by the thin band of infuscation along the distal wing margin (this band of infuscation thick in C. lobatus ).

Description. Body length: 5.8–6.5 mm. Wing length: 5.2–6.0 mm. Male. Head. Black, face black; 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 very small, dark brown; proboscis brown, extending slightly below eye in lateral view; antennal segments black to brown; postpedicel subtriangular, length subequal to width; arista about equal to head height.

Thorax: Mesoscutum, scutellum, and pleura dark brown to black throughout, with a few metallic greenish highlights laterally; thoracic setae black: 4 dc; 2 np; 2 ph; 1 pa; 1 + 1 sc; ac uniseriate; halter stem and knob white.

Legs: CI yellowish white, CII and CIII brown; FI and FII yellowish white, FIII yellowish basally, dark brown on apical one-half; TiI all yellow; TiII yellowish brown; TiIII yellow only at extreme base, otherwise legs brown; femora without MSSC; TiII with 6–8 strong black setae basally, medially and apically on lateral and anterior surfaces, smaller stiff black setae and hairs along entire mesal surface (MSSC?); remainder of leg segments without MSSC.

Wing ( Fig. 6 ): Pale smoky throughout; costal region straight, not bulging; cell r2+3 not infuscated; R2+3 and R4+5 parallel at wing margin, about as wide as distance between R4+5 and M1+2 at wing margin; vein M1+2 straight to swing margin; apex of wing not falcate just below end of vein M1+2; thick spot of color at apex of wing separated from very indistinct, thin band of infuscation along distal wing margin from end of M1+2 to vein CuA1 (MSSC); vein CuA1 with thick infuscation from crossvein dm-cu to wing margin (MSSC); crossvein dm-cu perpendicular to radial veins; anal region with distinct lobe.

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

Female. As in male except for lack of MSSC.

Types. Holotype ɗ (BPBM 16,660) [BPBM 101267], 23 ɗ [BPBM 101268], and 7Ψ BPBM 101269 paratypes from FRENCH POLYNESIA: Society Is: TAHITI NUI: Punaruu River, 1–2 km E. Punaauia on way to Plateau Tamanu, 140–160 m, 20 Jul 2006, on seeps next to stream, N. Evenhuis, P. O’Grady. Other paratypes: FRENCH POLYNESIA: Society Is: TAHITI NUI: 4ɗ [BPBM 101270], 3 Ψ [BPBM 101271], Col Urufaau, tunnel and seeps along road, 700 m, 16 Jul 2006, N. Evenhuis, P. O’Grady (see Fig. 13 ); 1ɗ [BPBM 101272], 1 Ψ [BPBM 101273], same data except: 0.5 km S. Col Urufaau, 575 m; 3 ɗ [BPBM 101274], 1Ψ [BPBM 101275], same data except: 2.5 km S. Lac Vaihiria, 350 m, sweeping cascades and dark wet boulders, P. O’Grady; 1ɗ [BPBM 101276], Cascades de Tefauromai, Vaipuu Rivière below Cascade Haamarere Rahi, on stream rocks, 31 Mar 2007, N. Evenhuis; 1ɗ [BPBM 101277], Papenoo Valley, Mar 1955, N.L.H. Krauss; 1Ψ [BPBM 101278], Papeete, Mar 1955, N.L.H. Krauss. TAHITI ITI: 2 ɗ [BPBM 101279], 6Ψ [BPBM 101280], Rt. 33 on road to Taravao Plateau, on stream rocks above captage, 30 Mar 2007, R.A. Englund. Holotype in BPBM. Paratypes in BPBM, EMEC, and USNM. All except the Krauss specimens are preserved in ethanol.

Remarks. During initial collecting and sorting I had grouped this species and C. lobatus into the same “morphospecies”. However, close examination of the wing characters showed consistent differences in the markings and apical shape of the wing as well as mid tibial coloration differences that separate the two.

Etymology. The specific epithet derives from the Greek ρηεοσ = “flowing” + κρενε = “spring”; referring to the habitat of this species being found along seeps and wet rocks adjacent to streams

Figures

FIGURES 5 – 9. Campsicnemus lobatus group wings. 5. C. lobatus; 6. C. rheocrenus; 7. C. borabora; 8. C. paralobatus; 9. C. tunoa.

FIGURES 10 – 13. Localities for species of the lobatus group. 10. Lower Fa’anui stream, Bora Bora. Photo by Ron Englund. 11. Afareiatu Cascade, Moorea. Photo by Patrick O’Grady. 12. Small unnamed cascade below Cascade Vaimahuta, Tahiti (unofficially named Craig’s Cascade). Photo by Doug Craig. 13. Seep at Col Urufau, Tahiti. Photo by Patrick O’Grady.