Cymatopus ventralis, Masunaga, Kazuhiro & Evenhuis, Neal L., 2012

Masunaga, Kazuhiro & Evenhuis, Neal L., 2012, Two new species of the genus Cymatopus Kertész from the Mariana Islands (Diptera: Dolichopodidae), Zootaxa 3159, pp. 36-46 : 43-45

Cymatopus ventralis sp. nov.

( Figs. 1 , 2 B, 3C–D, 6, 7)

Type material. HOLOTYPE: 3 labeled: Commonwealth of the Northern Marianas: Saipan: Obyan Beach, 13.ii.2001, K. Masunaga leg. ( LBM). PARATYPES: SAIPAN: 293, 42Ƥ, same data as holotype ( LBM); Commonwealth of the Northern Marianas: ROTA: 1093, 158Ƥ, Swimming Hole, 12.ii.2001, K. Masunaga leg. ( LBM); 23, 3Ƥ, same locality, 13.v.2004, R. Zack leg. ( WSU); 2Ƥ, coral beach around Sunset Motel, R. Zack leg. ( WSU). GUAM: 83, 8Ƥ, Inarajan Pool, 9.ii.2001, K. Masunaga leg. ( LBM); 1673, 213Ƥ, Tagachang Beach, 11.ii.2001, K. Masunaga leg. ( LBM); 133, 17Ƥ, Tanguisson Beach, 17.iii.2010, R. Englund leg. ( BPBM); 23, 2Ƥ, Mangilao Village, University of Guam campus, Marine Biology Lab area, 13°25.714'N, 144°47.913'E, 20.v.2004, R. Zack leg. ( WSU).

Etymology. The specific name, an adjective, is Latin ventralis (abdominal), referring to the characteristic shape of the male sixth sternum.

Diagnosis. Small species (2.0– 2.6 mm in body length) with 4 dorsocentral bristles, long hairs on male middle and hind tibiae, 2–3 short strong bristles on male hind tibia, male abdominal sternum 6 with conspicuous process.

Description. Male. Body length 2.0– 2.3 mm; wing length 2.0– 2.4mm. Head: 1.7 times as high as long, 1.0 times as wide as high. Frons wide, metallic green with grayish brown pollinosity, but brown above antennal sockets; frontal bristle 0.9 times as long as ocellar bristle. Ocellar tubercle distinct, with 2 strong ocellar bristles. Occiput metallic green with grayish pollinosity. Postocular ciliation erect, black. Face and palpus brown with dense grayish pollinosity, tinged with green. Face at narrowest part 0.15 times as wide as head. Palpus 1.5 times as long as wide, clothed with long setae. Proboscis short, 0.5 times as long as eye height. Antenna brown; scape 1.2 times as long as deep, bare; pedicel as long as deep; 1st flagellomere 1.1 times as long as basal thickness; arista apical, 4.0 times as long as 1st flagellomere. Thorax: dark brown with grayish white pollinosity. Thoracic bristles black. Chaetotaxy: no acrostichals; 4 dorsocentrals, of which anterior 3 equal in length and 4th 1.2 times as long as them; 1 each of postpronotal, posthumeral, sutural, postsutural, supra-alar, and postalar setae; notopleuron with 2 setae, upper one 1.5 times as long as lower; posthumeral seta 1.3 times as long as humeral seta, postalar seta 2.2 times as long as supra-alar seta; 2 long scutellum setae 2.6 times as long as scutellum. Proepisternum with 2 long setae. Legs: Coxae concolorous with pleura. Femora and tibiae dark brown with rather grayish pollinosity and tinged with green; apical parts of femora and basal parts of tibiae pale brown. Foreleg ( Figs. 6 A-B): Coxa with short setulae irregularly arranged on anterior surface and row of apical marginal setae. Femur 4.6 times as long as thick, 1.2 times as long as tibia, thickening through basal 1/6 of length then tapering apically; tibia straight with strong posteroventral setae on tip. Tarsomeres 1–5 simple, their relative lengths 20:8:6:6:10. Midleg: Coxa with 3 conspicuous outer setae and several setae near tip on anterior surface. Trochanter with row of ventral setae and some setae on anterior side. Femur 1.2 times as long as tibia, with 2 anterodorsal, 1 anterior, 1 anteroventral, 1 ventral, 2 posterodorsal, 1 posterior, and 1 posteroventral rows of setae, of which posteroventral row longest. Tibia with 1 thick anterodorsal and 1 thick posterodorsal setae on basal 1/5, and 1 long ventral and 2–3 long posteroventral setae near tip, longest one 0.4 times as long as tibia. Tarsomeres 1–5 simple, their relative lengths 37:14:9:7:10. Hindleg ( Figs. 6 C–D): Coxa with conspicuous outer seta on basal 2/5. Trochanter with 2 long ventral setae, of which distal one longer. Femur 1.6 times as long as tibia, thickest at basal third, then gradually tapering apically and ventrally straight, with 2 dorsal, 1 anterodorsal, 1 anterior, 1 anteroventral, 1 posterodorsal, 1 posterior, and 1 posteroventral row of setae, of which posteroventral row thickest. Tibia with ventral margin expanding through proximal 2/3 of length, with a few short, thick, curved ventral setae on widest part, then slightly tapering apically. Apical part of tibia extended ventrally. Tibia with 1 anterodorsal, 1 anteroventral, 1 ventral, 2 posterodorsal, and 1 posteroventral rows of setae, of which ventral row longest on apical third of tibia. Tarsomere 1 with 3 long ventral setae near base, these 0.4 times as long as their segment. Tarsomeres 1–5 simple, their relative lengths 34:11:7:6:10. Wing ( Fig. 3 C): Long and darkened. Apical section of M3+4 4.8 times as long as discal crossvein. Calypter dark brown with brown fringe. Halter yellowish brown. Abdomen ( Figs. 7 D–E): Abdominal terga tinged green with grayish pollinosity and with short, black setae. Sterna 2–4 each with several long setae, sternite 6 with conspicuous setae and processes as figured ( Fig. 7 D). Hypopygium ( Figs. 7 A–C) small and compact, tinged green with dense grayish pollinosity; cercus long, tapered, dorsal margin curved ventrally, with many setae apex, and with 3 wide, blade-like bristles and 1 dorsal seta; hypandrium flattened laterally and pointed; surstylus narrow and long, with 4 long ventral setae subapically and blade-like bristle apically; epandrial lobe short with 2 long setae on apex. Female. Body length 2.1–2.6 mm; wing length 2.1–2.6 mm. Face at narrowest part 0.2 times as wide as head. Proboscis 0.3 times as long as eye height. Tibia of foreleg with strong posteroventral seta subapically. Relative lengths of tarsomeres 1– 5 of foreleg 28:9:7:7:10. Tibia of midleg with anterodorsal seta and posterodorsal seta on basal 1/4 and circlet of apical setae, posteroventral one longest. Relative lengths of tarsomeres 1–5 36:14:9:6: 10 in midleg, 31:15:9:7: 10 in hindleg. Apical section of M3+ 4 in wing 3.8 times as long as discal crossvein ( Fig. 3 D).

Remarks. Externally, this new species is similar to Cymatopus longipilus , which is known from Christmas Island (Indian Ocean) and Thailand, but C. longipilus has the following set of characters different from those of the new species: male middle tibia with more than 10 long setae near tip; male hind tibia lacking, strong, thorn-like down-curved bristles near middle (cf. Parent 1935b).

Distribution. Commonwealth of the Northern Mariana Islands (Saipan, Rota); Guam ( Fig. 1 ).

Figures

FIGURE 1. Map of Guam and the Northern Mariana Islands. Names of islands from which the present samples were taken are underlined.

FIGURE 2. Adult males of Cymatopus species in lateral view. (A) C. femoralis sp. nov.; (B) C. ventralis sp. nov.

FIGURE 3. Wings of Cymatopus species. (A) C. femoralis sp. nov., 3; (B) C. femoralis sp. nov., Ƥ; (C) C. ventralis sp. nov., 3; (D) C. ventralis sp. nov., Ƥ.

FIGURE 6. Cymatopus ventralis sp. nov., legs of male, SEM. (A, B) Fore leg in anterior view; (C) Hind leg in anterior view; (D) Hind leg in posterior view. Scale bars: 100, 200 μm.

FIGURE 7. Cymatopus ventralis sp. nov., male genitalia. (A) Hypopygium in lateral view; (B) Cercus in lateral view; (C) Surstylus in lateral view; (D) Male sternite 6 in lateral view; (E) Detail of strong bristles of sternum 6 (location marked by arrow) in ventral view.