Echinosoma roseiventre Kamimura & Nishikawa

Kamimura, Yoshitaka, Nishikawa, Masaru & Lee, Chow-Yang, 2016, A new earwig of the genus Echinosoma from Penang Island, Peninsular Malaysia, with notes on the taxonomic and nomenclatural problems of the genus Cranopygia (Insecta, Dermaptera, Pygidicranidae), ZooKeys 636, pp. 51-65 : 52-55

Echinosoma roseiventre Kamimura & Nishikawa sp. n. Figs 1a, 2-6, 7-9

Echinosoma sp.: Kamimura et al. 2016: 240, figs 9, 10.

Diagnosis.

Echinosoma roseiventre sp. n. is a small species less than 8 mm including the forceps. This species differs from all other similar sized species of Echinosoma with the combination of the following characters: abdomen uniformly reddish brown or rosy without a distinct pattern; ultimate tergite not pubescent, but with small rounded swellings; pygidium broader than long; virga very long, more than five times longer than parameres, tubular and simple.

Description.

Holotype (male): length of body (without forceps): 7 mm. Length of forceps: 0.9 mm. Head width: 1.5 mm. Pronotum width: 1.6 mm. Pronotum length: 1.1 mm.

Color: General body color dull smoky black but abdomen, especially caudal part, pygidium, and forceps reddish brown or rosy (Fig. 1a). Mouth parts brownish. Antennae dark brown except for first three segments dirty white. Legs dirty white but femora with a broad fuscous band near the base. Caudal margin of tegmina with distinct, narrow whitish band. First abdominal segment whitish. Body covered with obtuse bristles sparsely. Head (Fig. 2) slightly broader than long; frons convex; transverse and median suture indistinct; caudal margin feebly emarginated in middle. Antennae (Fig. 3); 17 segments (left side partly broken, 16 segments remaining), segments mostly stout; 1st expanded apically, nearly half long as the distance between antennal bases; 2nd short, quadrate, almost as long as broad; 3rd long, twice as long as broad; 4th and 5th short, as long as broad; 6th and beyond gradually becoming longer and narrowing basally rendering some segments subpyriform. Eyes long, approx. as long as the post-ocular length. Post-ocular margin with a row of five long bristles. Pronotum (Fig. 2) broader than long; surface rough; sides rounded; frontal and caudal angles weakly and strongly rounded, respectively; caudal margin convex with distinct emargination in middle; prozona distinctively raised; median sulcus week but visible; row of long bristles on frontal and lateral margins. Tegmina almost as long as pronotum; surface rough; humeral angle weak and anal angle shortly rounded off to show a small, triangular scutellum; caudal margin obliquely truncate, outer and caudal margins with long bristles. Hind wings wanting. Legs stout; femora not compresed, ecarinate; arolium small; hind tarsi with 1st segment longer than the third. Abdomen stout, more or less parallel-sided, except first three segments narrowed; sides of segments almost straight; tergites with scattered granules or very short obtuse bristles with whitish apex; first two tergites and lateral sides of 3rd tergites onward with long bristles near caudal margins. Penultimate sternite (Fig. 4) transverse, narrowed posteriorly with caudal margin being nearly half of the anterior, widely emarginated. Ultimate tergite (Fig. 5) transverse, with small rounded swellings above the base of forceps; caudal margin almost straight. Pygidium short, rectangular, transverse. Forceps (Fig. 5) short, strongly curving inwards, tapering apically; surface, smooth at tips. Genitalia (Figs 6-9) with slender, finger-like parameres with obtuse tips and broad base (Fig. 7); penis lobe almost twice length of parameres; virga very long, more than five times longer than parameres, tubular and simple (Figs 6, 8); penis lobes also enclose a funnel-shaped sclerite at the base of virga, and a long ellipse sclerite distally (Fig. 9).

Paratype (male). Length of body (without forceps), 6.5 mm; length of forceps, 0.8 mm; head width, 1.2 mm; pronotum width, 1.2 mm; pronotum length, 0.8 mm. Antennae broken, five (right) and eleven (left) segments remaining. Tegmina longer, approx. 1.5 times longer than pronotum. Penultimate sternite not strongly narrows posteriorly, almost rectangular.

Female. Unknown.

Type series.

Holotype: 1 male (genitalia mounted in Euparal between two coverslips and attached to the pin of the specimen), Bukit Jambul, Penang Island, West Malaysia, 27.XI.2012, Y. Kamimura leg. [OMNH]. Paratype: 1 male (genitalia mounted in Euparal between two coverslips and attached to the pin of the specimen), same locality as holotype, 24.VI.2012 (8.VII.2012 emerged from a nymph), Y. Kamimura leg. [LKCNHM].

Distribution.

Penang Island, Peninsular Malaysia

Etymology.

The specific epithet refers to the characteristic rosy abdomen of this new species.

Remarks.

Echinosoma roseiventre sp. n. is very close to Echinosoma andamanensis Srivastava, 1988, described from India. Currently these two species can only be distinguished by differences in the length of the virgae (shorter than five times the parameres in Echinosoma andamanensis ), the shape of the pygidium (longer than broad in Echinosoma andamanensis ), and body coloration ( Echinosoma andamanensis is generally dull smoky black but the abdomen, pygidium, and forceps are shiny; Srivastava 1988).

In addition to the species listed in the key below, Echinosoma rufomarginatum Borelli, 1931, which Hincks (1959), Steinmann (1986) and Srivastava (1988) treated as a doubtful species, also has a small body size (body length with forceps of ~11 mm; Hincks 1959). However, according to the original description by Borelli (1931), the male penultimate sternite of this species has a very deep emargination on the caudal margin. The male genitalia of Echinosoma burri Hincks, 1959, recorded from Java and Sumatra, are very similar to those of Echinosoma roseiventre sp. n., but the body size is much larger (male body length with forceps of 18-20 mm; Hincks 1959).