Eugubinus araneus Distant, 1903

Ghate, Hemant V., Boyane, Swapnil S. & Webb, Michael D., 2021, Description of the adult of the thread-legged assassin bug Eugubinus araneus (Hemiptera: Reduviidae) from India, with comments on other congeneric species, Zootaxa 4990 (2), pp. 291-304 : 293-298

Eugubinus araneus Distant, 1903

( Figs. 1–3 , 5–23 )

Eugubinus araneus Distant, 1903a: 253 . Syntype (s): India, Uran (near Mumbai); BMNH.

Eugubinus araneus: Distant (1903b: 206) (redescription, illustration), Wygodzinsky (1953: 218) (in key), Wygodzinsky (1966: 243), Maldonado (1990: 84) (catalogue). Ambrose (2006: 2396) (checklist).

Description of adult male and female (based on 3 ♂♂ and 2 ♀♀):

Slender insect of moderate length (from tip of head to tip of abdomen 12.5–13.5 mm).

Colouration: Body colour mostly piceous with pale or ochraceous markings on head, pronotum and abdomen, along with pale annuli on fore leg, antennae, mid and hind legs ( Fig. 5 ). Head with a pair of shining, oblique lines forming ‘V’ in front of transverse sulcus ( Fig. 9 ) and an indistinct pale area immediately behind each eye laterally ( Fig. 6 ). First antennal segment with seven pale annuli which are shorter than dark areas separating them; second segment with five pale annuli, including very small basal one; third segment with a single small basal annulation. Head uniformly piceous ventrally, with a pair of oval, very shiny areas, one on each side, behind eyes ( Fig. 10 ). Anterior lobe of pronotum dark brown to piceous; posterior lobe pale brown with median and lateral oblique ochraceous lines; prosternum uniformly piceous ( Figs. 6 , 12, 13 ). Fore legs with coxae uniformly dark, femora with an apical small pale area and two submedian obscure pale brownish patches (clearer in wet specimens), long posteroventral spines white with dark tips; tibia with two incomplete subbasal pale annuli; tarsus almost entirely brown ( Fig. 11 ). Mid and hind coxae and trochanters dark brown with some pale areas. Mid and hind femora with numerous pale annuli, in between areas with dark annuli or brownish mottling, hind femora white at tip while mid femora brown at apex but with subapical white ring. Tibiae with many pale annuli that are longer than dark brown interspaces but without mottling; tarsi pale in basal part and dark distally ( Fig. 5 ). Forewings very pale brown with dark brown veins ( Figs. 15, 16 ). Hind wings translucent with dark veins.Abdomen dorsally dark brown, ventrally with median spots on each segment (occasionally joined by indistinct line of similar colour, or with additional pair of spots on either side of median line, or median line might occasionally be very distinct and broad); connexivum with pale patches in segments three to six; spiracles all white and slightly elevated; seventh abdominal segment dorsally with a median ochraceous line and ochraceous outer angles. Pygophore dark brown. Parameres with indistinct dorsal pale line and pale subapical area, remaining part and extreme tip dark ( Figs. 14 , 17 ).

Structure: Head oval, considerably narrowed behind eye to small neck, slightly convex dorsally; eyes large, globular, reaching dorsal and ventral margin of head in lateral view; prominent transverse sulcus present between eyes, its posterior margin not reaching hind border of eye; anteocular slightly longer than postocular; antenniferous tubercles situated dorsally at about midway between eye and apex; antennae long, first segment longest (ca. 5 mm), longer than head and pronotum together (ca. 4 mm), second segment shorter, third shortest, fourth slightly longer than third; labium robust, strongly bent between first and second visible segments, first and second visible segments strongly incrassate ( Fig. 6 ).

Thorax with pronotum covering mesonotum; posterior lobe of pronotum about 1.4 times longer than anterior lobe; anterior lobe narrower than posterior lobe, broadest at anterior angles and narrowed behind but not pedunculate; posterior lobe set at an angle, sloping towards anterior lobe, broadest at humeral angles, with a pair of strong, oblique carinae enclosing mid-dorsal, elevated area in between ( Fig. 6 ) and with median very short carina not reaching posterior margin; posterior margin emarginate, humeral angles subprominent ( Fig. 12 ). Scutellum very small. Prosternum with median, indistinct longitudinal carina; mesosternum and metasternum short, latter with short median carina in distal one third ( Fig. 13 ).

Abdomen narrow, almost parallel-sided except in seventh segment (which has lateral dilation) ( Fig. 14 ), dorsally more or less flat, ventrally slightly convex; connexivum narrow.

Male pygophore dorsally flat, ventrally very convex, and laterally slightly compressed ( Figs. 17–19 , respectively), with prominent median, superoposterior spine. Parameres short, curved around median spine, pointed apically ( Fig. 20 ). Phallus symmetrical, articulatory apparatus about as long as phallosoma. Phallosoma weakly sclerotized, without projections; endosoma covered with many fine spinules ( Figs. 21, 22 ).

Female seventh tergite with prominent lateral projections; genital segments oblique or subvertical, less sclerotized.

Nymph (5th instar). Colouration of 5th instar nymph is almost exactly as described and illustrated by Distant (1903b) and seen in the two syntypes deposited in BMNH ( Fig. 23 ) hence it is not repeated here. Photographs in dorsal and lateral profile, showing colouration, are provided ( Figs. 3 , 7, 8 ). A single nymph (found dead in web) was collected and preserved, another live one was left undisturbed to observe feeding and movement. Measurements of the preserved nymph are given here.

Measurements (in mm): (Adults 2 ♂♂ / 2 ♀♀): Total body length 12.5/13.5; total length of head 1.00/1.05, length of anteocular part 0.30/0.30, of postocular part 0.27/0.30; eye diameter 0.37/0.30.Antenna: length of segment I 5.20/5.20, of segment II 4.00/4.10, of segment III 0.50/0.50, of segment IV 2.11/2.13. Length of labium 1.50/,1.55 of first visible segment 0.50/0.50, of second visible segment 0.50/0.45, of third visible segment 0.50/0.60. Length of pronotum 2.70/2.80 (anterior lobe 1.20/1.50, posterior lobe 1.20/1.60); Length of fore coxa 1.87/2.00, of fore femur 3.50/3.37, of fore tibia 2.50/2.50, of fore tarsus with claw 0.37/0.37; length of mid coxa 0.33/0.50, of mid femur 7.75/7.80, of mid tibia 9.00/10.00, of mid tarsus with claw 0.37/0.37; length of hind coxa 0.37/0.50, of hind femur 10.0/10.6, of hind tibia 14.5/14.5, of hind tarsus with claw 0.37/0.37. Length of forewing 6.50/6.80.

Nymph (single specimen): total body length 9.00; total length of head 0.70, Antenna: length of segment I 3.25, of segment II 2.75, of segment III 0.60, of segment IV 2.30. Labium: length of first visible segment 0.50, of second visible segment 0.30, of third visible segment 0.50. Length of pronotum 1.13. Length of fore coxa 1.25, of fore femur 2.13, of fore tibia 1.38, of fore tarsus with claw 0.50; length of mid coxa 0.35, of mid femur 5.00, of mid tibia 5.50, of mid tarsus with claw 0.25; length of hind coxa 0.43, of hind femur 5.50, of hind tibia, of hind tarsus with claw 0.25.

Type material examined. India: syntype nymph, “Uran nr. Bombay E.H. Aitken 1900.16”, “ Eugubinus araneus Dist. ”, “Living in nest of spider Theridium ”, “NHMUK 0103586728” ( Fig. 23 ); syntype nymph, same data except lacking the spider web data label, “NHMUK 0103586729”; both specimens deposited in BMNH .

Additional specimens examined. India: Daund , Pune, trapped in spider web, 4.xi.2017, leg. P. Pansare (1 ♂ 1 ♀); Lonavala, Pune, 17.xi.2017, leg. B. Sarode (1 live ♂, 1 live nymph, 1 ♀ trapped in web); Aundh Road, xii.2017, leg. B. Sarode (one mutilated ♂ trapped in web); all preserved specimens deposited in MCASCP .

Remarks. Distant (1903a) described Eugubinus araneus from an unspecified number of specimens with the following data: “Uran, near Bombay (Aitken, Brit. Mus.). Found living in nest of spider ( Theridium sp. )”. Note: Gravely (1915) commented that it is unlikely to be a web of Theridiid and the spider must be Cyrtophora cicatrosa (Stoliczka, 1969) (Araneidae) . Two specimens (nymphs) bearing this locality and collector data are present in the BMNH, including one with the spider web data. The syntypes compare fairly well with a nymph collected recently in Lonavala, Pune, India; the latter is therefore regarded to represent E. araneus , as is its associated adult.

Figures

FIGURES 1–4. Habitat and habitus of Eugubinus spp. 1, Habitat of E. araneus; 2, live female of E. araneus; 3, live nymph of E. araneus; 4, live female of E. intrudans.

FIGURES 5–8. Colouration of Eugubinus araneus Distant, 1903. 5, lateral habitus of male; 6, anterior half of body; 7, lateral habitus of nymph, 8, anterior half of nymph.

FIGURES 9–16. Structure of Eugubinus araneus Distant, 1903. 9, 10, head in dorsal and ventral view respectively; 11, fore leg in lateral view; 12, head and thorax in dorsal view; 13, thoracic sternum in ventral view; 14, abdomen in lateral view; 15, forewing in situ; 16, forewing. (All the images are of male)

FIGURES 17–22. Male genitalia of Eugubinus araneus Distant, 1903. 17–19, pygophore in dorsal, ventral and lateral views respectively; 20, parameres; 21, phallus in lateral view; 22, phallus everted.

FIGURES 23–25. Type specimens of Eugubinus spp. and their labels. 23, syntype (nymph) of E. araneus Distant, 1903 (body length 8.5 mm); 24, syntype male of E. intrudans Distant, 1915 (body length 13.0 mm); 25, syntype female of E. reticolus Distant, 1915 (actual size 13.0 mm).