Conchopus pacificus, Masunaga, Kazuhiro & Saigusa, Toyohei, 2010

Masunaga, Kazuhiro & Saigusa, Toyohei, 2010, A revision of the Hawaiian and Wake Island species of the genus Conchopus Takagi (Diptera, Dolichopodidae), Zootaxa 2729, pp. 1-35 : 27-34

Conchopus pacificus sp. nov.

( Figs. 15 , 16 , 17 , 18 f)

Diagnosis. Small-sized species (2.3–3.1 mm in body length) similar to C. minutus sp. nov. and characterized by 1st flagellomere 1.7 times as long as its basal thickness; halter brown. In male, M1+2 thickened, apical section of M3+4 2.6 times as long as discal crossvein; fore tarsomere 1 with large basal lobe 2/5 as long as tarsomere 1, strong ventral bristle beyond midlength, and moderately large apical swelling; longer dorsal bristle of fore tarsomere 2 slightly before middle; mid tibia cylindrical, without long erect bristles and setae on anterior and posterior surfaces; mid tarsomere 1 short setose; ventral lobe of hypopygium produced into slender distal prolongation.

Descriptions. Male: Body length 2.5–3.1 mm; wing length 2.8–3.1 mm. Head: l.8 times as deep as long; vertex and upper half of occiput densely dark-grayish-brown pollinose, greenish ground color entirely concealed. Face at narrowest point 0.13 times as wide as head, rather abruptly widening ventrally, widest ventral part twice narrowest point. Proboscis 0.4 times as long as eye height. Antenna 0.6 times as long as head; 1st flagellomere short, 1.1 times as long as 2 basal segments combined, 1.7 times as long as thick; arista 1.4 times as long as 3 antennal segments combined. Thorax: Mesonotum viewed from above humerus almost ash gray with slight brownish tinge; inverted Y-shaped dark area deep black, 1st and 2nd dc located in white marking, area surrounding 3rd dc and 2 supra-alar bristles brownish, presutural dark prolongation much reduced, very indistinct, recognizable as small, obscure dark area not connected with Y-shaped mark and located in front of sutural bristle; supra-alar area gray. Chaetotaxy: acrostichals 8–9 in number, almost uniserial, ending posterior at level of 2nd dc or midway between levels of 1st and 2nd dc. Propleurals 5–6, mesopleurals 6–7, arranged in 2 irregular rows along upper part of posterior margin of anepisternum, with lowermost setulae at ventral extremity of basalare; epimerals l. Scutellum with 1 or 2 outer marginals, and 2 strong inner bristles. Legs. Foreleg ( Figs. 15 a-b): Coxa with irregularly biserial inner row of weak setae, outer row reduced 1–2 strong subbasal bristles, submarginal bristles fairly strong, about 10 in number. Femur 4.8–5.2 times as long as thick, gradually tapered apically; preapical tubercle situated at 0.16–0.17 from tip; ventral setae of subbasal part of femur 0.4 times as long as thickness of femur. Tibia only slightly dilated apically, with 4–5 antero- and 2–3 posterodorsal short bristles distinct from dorsal setae; anteroventral setae strong, posteroventral setae slightly weaker than anteroventral setae, anterior preapical mass of setulae well developed. Tarsus 1.1 times as long as tibia. Tarsomere 1 short, weakly convex dorsally; basal lobe weakly developed, evenly rounded ventrally, 0.5 times as thick as long, 0.3 times as long as tarsomere 1, with 5–8 setulae arranged in row along ventral margin; ventral bristle very strong, nearly twice thickness of tarsomere 1 (latter measured through base of this bristle), situated 0.4 from tip; weakly raised keel ciliated with 3 setulae between basal lobe and ventral bristle; apical swelling of tarsomere 1 well developed, produced ventrally; anterior preapical cluster of setulae at level of posterior preapical bristle, centered l/4 from tip. Tarsomere 2 with 2 strong anterodorsal bristles, situated 0.3 from base, distal one slightly shorter than proximal one, situated 0.4 from base; much weaker additional bristles sometimes present beyond midlength. Tarsomeres 3–5 simple. Midleg ( Fig. 15 c): Femur strongly depressed dorsoventrally in apical half, there 0.4 times as thick as basal width, with anterior margin gently arched and posterior margin almost straight; about 10 anterior setae on apical 2/3 of femur becoming bristle-like distally, anteroventral bristles well developed (longest one towards base nearly as long as subbasal thickness of femur), longer and much more prominent than posteroventral setae. Tibia weakly depressed dorsoventrally, short setose, and 2 ordinary pairs of dorsal bristles, one subbasally, other near midlength. Tarsomere 1 with 2 anteroventral bristles on basal half, both being 2.5 times as long as width of tarsomere 1. Hindleg: Femur weakly tapered towards tip, with sparser setae on ventral surface. Tibia with shorter setae and posteroventral setae. Wing ( Fig. 18 f): 2.8 times as long as wide; basal portion of vein R4+5 incrassate, thicker than middle of R2+3 or Sc, distal crossvein slightly oblique; ratio of M1 to apical section of M1+ 2 l. 6–1.8; ratio of middle section of M3+4 to apical section of M3+ 4 l. 7. Halter brown, but knob dark brown. Abdomen ( Figs. 16 a-c): Sternum 4 with pair of strong, spine-like subventral bristles before middle; sternum 5 with subventral clusters consisting of 3 spines, subventral rows of setae uniserial in anterior portion, but mixed among scattered setae towards hind margin; sternum 6 trapezoidal in shape with small distal membranous area and pair of anterior apodemal processes, these being short, blunt and not divergent. Membranous portion of pedunculate process of sternum 6 0.5 times as long as process itself, with anterior margin much curved in basal half; anterior spinuli long and roughly napped posterior minute tubercles with very short pile-like point. Hypopygium ( Figs. 17 a-d): Cercus widest 1/3 from tip, apical dilated portion almost parallel-sided on basal half, with inner margin constricted and strongly produced distal tip. Ventral lobe flattened longitudinally, almost parallelsided with long posterodistal projection 0.5 times as long as main portion of process; apical margin of ventral lobe fringed with about 10 pale setae. Hypandrium with anterior and posterior processes subequal in length, and with lamellate dentation between them. Female. Similar to male, but face at narrowest part 0.24 times as long as head. Proboscis 0.67 times as long as eye height: Relative lengths of tarsomeres 1–5 31:25:15:8: 15 in foreleg; 52:33:21:10: 15 in midleg; 42:46:28:13: 15 in hindleg. Wing: apical section of M3+4 2.7 times as long as discal crossvein. Body length 2.3–2.6 mm; wing length 2.7–2.9 mm.

Material examined. HOLOTYPE ɗ, Leleiwi, Hawai‘i, 13.xii.2002, K. Masunaga leg. ( BPBM). PARA- TYPES ( BPBM, LBM, BLKU): Hawai‘i: 1ɗ, Kahalu‘u, Kona, Hawai’i, viii.1958, Y. Kondo leg.; 3Ψ, Kailua- Kona, 29.ix.1966, W.J. Voss leg.; 19ɗ1Ψ, Hilo, 23.iii.1967, J.R. Vockeroth leg.; 15ɗ8Ψ, Kalapana Pk., 24.iii.1967, J.R. Vockeroth leg.; 283ɗ250Ψ, Leleiwi, 13.xii.2002, K. Masunaga leg.; 118ɗ90Ψ, Honaunau, 14.xii.2002, K. Masunaga leg.; 2ɗ, Kapa‘a Beach, 14.xii.2002, K. Masunaga leg.; 108ɗ80Ψ, Black sands beach, 15.xii.2002, K. Masunaga leg.; Maui: 4ɗ, Makena, 10.xii.2002, K. Masunaga leg. O‘ahu: 1Ψ, Waianae, 29.v.1966, T. Saigusa leg.; 5Ψ, Makapu‘u Pt., 21.v.1967, J.R. Vockeroth leg.; 3Ψ, Hanauma Bay, 23.iii.1967, J.R. Vockeroth leg.; 23ɗ, Sandy Beach Park, 19.xii.2002, K. Masunaga leg. Kaua‘i: 7ɗ2Ψ, Po‘ipu Beach, 6.xii.2002, K. Masunaga leg.; 5ɗ, Po‘ipu Beach, 8.xii.2002, K. Masunaga leg.; 23ɗ27Ψ, Po‘ipu Beach, 9.xii.2002, K. Masunaga leg. Wake: 1ɗ1Ψ, 30.vii.1923, on sand, E.H. Bryan Jr. leg.; 1Ψ, 5.viii.1923, on sand, E.H. Bryan Jr. leg.

Distribution. Hawaiian Islands (Hawai‘i, O‘ahu, Kaua‘i) and Wake Island.

Etymology. The species is named after the type locality, which is situated in the center of the Pacific Ocean.

Remarks. This new species most closely resembles Conchopus minutus sp. nov. and Conchopus menehune sp. nov. in having the thickened M1+2 and M1, short setose mid tibia in males, but the males of the latter two species have the following combination of characters different from those of the present new species: halter yellow; and fore tarsomere 1 with ventral bristle situated near or beyond the middle.

This species is distributed in both Wake Island and the Hawaiian Islands, separated by 3,000 km. Annexed by the United States in 1899, Wake Island was placed under the jurisdiction of the US Navy Department in 1935, and that same year a modern airport was established ( Bryan 1959). There is a possibility that some animals were introduced from the Hawaiian Islands to Wake Island at that time. However, the specimens from Wake Island examined in this study were collected by the Tanager Expedition in 1923, well before any significant construction had been done. Although rats were present on Wake Island by that time ( Bryan 1959), their source is unclear, and we think most likely that C. menehune occurs naturally there.

Figures

FIGURE 15. Conchopus pacificus sp. nov., legs of male: (a) left foreleg in posterior view; (b) distal part of tibia, tarsal segments 1 – 2 of right foreleg in anterior view; (c) left middle femur in anterior view.

FIGURE 16. Conchopus pacificus sp. nov., male abdominal sterna: (a) 1 st (top) to 5 th (bottom); (b) pedunculate process in lateral view; (c) sternum 6.

FIGURE 17. Conchopus pacificus sp. nov., male genitalia: (a) ventral lobe; (b) cercus; (c) hypandrium in lateral view; (d) hypandrium in dorsal view.

FIGURE 18. Male wings of species of Conchopus: (a) Conchopus acrosticalis (Parent); (b) Conchopus ciliatus sp. nov.; (c) Conchopus crassinervis sp. nov.; (d) Conchopus minutus sp. nov.; (e) Conchopus menehune sp. nov.; (f) Conchopus pacificus sp. nov.