Myrmecolax pachygnathus, Lu & Liu, 2014

Lu, Xiumei & Liu, Xingyue, 2014, Discovery of the twisted-wing parasite family Myrmecolacidae (Insecta: Strepsiptera) from China, with description of two new species of the genus Myrmecolax Westwood, 1861, Zootaxa 3881 (4), pp. 385-395 : 386-390

Myrmecolax pachygnathus sp. nov.

( Figs. 1–3 )

Description. Male. Total body length 1.67 mm.

Head transversely wider than metathorax, hypognathous; anterior yellow brown, covered with dense hairs; frons yellow brown, anteriorly produced and nose-like; gena pale brown; clypeus dark brown, covered with dense short hairs, slightly concave (length of head 115.51 µm, width 218.14 µm, width between compound eyes 238.54 µm).

Compound eyes black brown, semiglobular, composed of ~18 large ommatidia, which are widely separated with interval densely covered by microtrichia in lateral and dorsal view; ventral ommatidia slightly larger and less closely neighbored to each other than dorsal ones. Number of ommatidia 18±3.

Antenna 7-segmented and yellow-brown in colour. 1 st and 2 nd antennomeres short (length of 1 st antennomere 85.32 µm, length of 2 nd antennomere 59.70 µm). 3 rd antennomere with an extremely long, broad, flat, sharply tipped, flabellum, which surpasses middle of 7 th antennomere (length of 7 th antennomere 41.56 µm). 4 th antennomere rather short, wider than long (length of 4 th antennomere 34.76 µm, proximal width 24.11 µm, distal width 31.49 µm). 5 th –7 th antennomeres long, gradually narrowed distad. 5 th antennomere longest among other antennomeres (length of 5 th antennomere 463.52 µm). 7 th antennomere longer than 6 th antennomere, with an acutely pointed tip (length of 6 th antennomere 275.81 µm, length of 7 th antennomere 420.21 µm).

Mandible palp-shaped, translucent, dark brown, glabrous and smooth, proximally wide, but medially narrowed and slightly incurved, distally slightly broadened, with a sharp tip, which is crossing to the other one (length of mandible 232.44 µm). Labrum absent. Maxillary palp 2-segmented, dark brown, with dense hairs; 1 st segment short, broad, dark brown; 2 nd segment thick, sickle-shaped, acutely tipped, whose length is four times as long as wide, elongated to ventral side, medially curved inward but not crossing to the other one; distinctly a thin brownish sclerotized strip extending latered between prementum and submentum; mouth opening circular (length of 1 st segment 241.80 µm, width of 59.81 µm, length of 2 nd segment 293.19 µm).

Thorax dark brown, strongly sclerotized, with dense hairs. Pronotum ring-like, medially arched, twice as long as mesonotum, arcutely convexed on anterior margin and medially semicircular concaved on posterior margin (length of pronotum 73.84 µm, width 278.56 µm).

Mesonotum saddle-like, medially semicircular convexed on anterior margin and arcuately convexed posterior margin (length of mesonotum 74.12 µm, width 377.64 µm). Prescutum slightly wider than scutum and pronotum, with acute angles; scutum slightly shorter than pronotum, with rounded lateral margins; scutellum transversely extending into a strip-shaped plate (length of scutellum 107.82 µm, width 194.43 µm, length of postlumbium 86.93 µm, width 297.56 µm, length of postscutellum 396.02 µm, width 298.66 µm).

Metathorax well developed, longitudinal. Prescutum nearly pentagon, slightly bulge at middle, with triangularly protruding anterior margin. scutum separated into two nearly rectangle, anteriorly rounded parts by distinct dark brown sutures, which are parallel, fusing at distal, and the posterior part rectangular in dorsal view; scutellum subtriangular, laterally margined dark brown; postlumbium lip-shaped, yellow; postscutellum cupshaped, gradually bending ventrad at posterior 3/4, with a straight posterior margin.

Legs brown, but femora much paler; coxae of fore- and midlegs broad and flat; trochanter of hind leg small, subsemicircular; tarsi 4-segmented, without tarsal claws, with translucent membrane anteriorly; 1 st tarsomere trapezoidal, with one sensory organ; 2 nd –4 th tarsomeres subtriangular. Lengths of fore coxa, femur, tibia, and tarsi: 274.64 µm, 340.20 µm, 253.10 µm, 179.78 µm, lengths of 1 st –4 th fore tarsomeres: 75.62 µm, 69.39 µm, 100.52 µm, 78.45 µm. Lengths of mid coxa, femur, tibia, and tarsi: 264.05 µm, 351.62 µm, 276.88 µm, 220.75 µm, lengths of 1 st –4 th mid tarsi: 125.59 µm, 75.30 µm, 89.34 µm, 82.15 µm. Lengths of hind trochanter, femur, tibia, and tarsi 67.63 µm, 235.38 µm, 128.29 µm, 126.36 µm, lengths of 1 st –4 th hind tarsi: 102.39 µm, 82.33 µm, 88.30 µm, 69.90 µm.

Halteres slender, broad, long, weakly sclerotized; proximally with a dark brown longitudinal vein-like line at middle, distal part ovoid (length of haltere 441.48 µm).

Hind wing broad, fan-shaped, translucent, pale brown, with dark brown veins; C and Sc fused into a thick vein, not reaching anterior margin; R 1 thick, almost ending at distal 1/4; R 2 detached, distally bifurcated; R 3 detached, reaching distal margin; R 4 with thick posterior part and weakly distal part, ending at middle; R 5 long, much darker, but proximally detached, reaching distal margin; MA 1 very short; MA 2 simple, reaching distal margin; CuA thin, slightly shorter than MA 2, almost reaching distal margin; CuP weak, long, almost parallel to anal margin. Length of hindwing 1.45 mm.

Abdomen dark brown; 10-segmented; tergites I–III gradually narrowed but tergites III–VIII gradually widened; segment I reduced, with rounded lateral margins; segments II long, slightly covered by postscutellum. Segment IX, elliptical in caudal view, extending ventrally as an elongate and grooved subgenital plate; lateral margins strongly sclerotized and incurved; posterior margin slightly concaved. Segment X small, shovel-shaped, with dorsally curved lateral margins. Aedeagus hook-like, arcuately curved anteriorly, with arcuate distal margin; body of aedeagus straight, gradually narrowed upwards; dorsal hook straight, slightly longer than ventral projection, with acute tip, directed from body of aedeagus by obtuse angle; ventral projection thinner than dorsal hook, with acute tip. Length of aedeagus 185.82 µm.

Female and host. Unknown.

Type material. Holotype ♂, CHINA: Guizhou Prov., Dushan [25°38′2.50″N, 107°33′11.48″E], VII.1981, collected by light trap, Wangmao Chen & Binghua Chen ( CAU).

Etymology. The specific epithet is derived from Latin pachygnathus , in reference to the broad maxillary palp in the new species.

Remarks. The new species similar to Myrmecolax furcatus Bohart, 1951 from Philippines by having similar distally bifurcated detached vein with anterior branch directed toward wing base, but can be distinguished from M. furcatus by the longer flabellum of 3 rd antennomere, the slightly bigger ratio of distance between internal margins of compound eyes and the diameter of a compound eye, and the more conspicuous and longer dorsal hook of the aedeagus.

The new species also resembles Myrmecolax odontognathus Kogan & Oliveira, 1964 from New Guinea by having similar aedeagus, in which the dorsal process is almost as long as ventral projection and an acute angle to the aedeagus, but it differs from M. odontognathus by the shorter body length, the conspicuously longer flabellum of 3 rd antennomere, and the bigger ratio of distance between internal margins of compound eyes and diameter of a compound eye.

Figures

FIGURE 1. Myrmecolax pachygnathus sp. nov., holotype male. A. Head, thorax and abdomen, dorsal view; B. Right hindwing. Scale bars = 250 µm.

FIGURE 2. Myrmecolax pachygnathus sp. nov., holotype male. A. Foreleg; B. Midleg; C. Hindleg; D. Mandible and maxillary palpi, ventral view; E. Aedeagus, left lateral view. Scale bars = 250 µm for A–C and 100 µm for D–E.

FIGURE 3. Myrmecolax pachygnathus sp. nov., holotype male. A. Head, frontal view; B. Head, left lateral view. Scale bars = 500 µm.