Sesieutes minuatus, Dankittipakul & Deeleman-Reinhold, 2013

Dankittipakul & Deeleman-Reinhold, 2013, Delimitation of the spider genus Sesieutes Simon, 1897, with descriptions of five new species from South East Asia (Araneae: Corinnidae), Journal of Natural History 47 (3), pp. 167-195 : 180-182

Sesieutes minuatus sp. nov.

( Figures 1 C,D, 2 C, 3 L, 5 A–F)

Type material

Holotype. ♂, Thailand, Chanta Buri Province, Nam Tok Plieu Khao Sabap National Park , 100 m semi-evergreen rainforest, 27–28 August 1992, leg. P.J. Schwendinger ( MHNG, 1274) .

Paratypes. One ♀, data as holotype ( MHNG, 1274) . 1♂, 2♀, Nam Tok Plieu Khao Sabap National Park , 50–100 m semi-evergreen rainforest, 12–13 November 1998, leg. P.J. Schwendinger ( MHNG, 1158) . 2♀, Trat Province, Ko Chang, west side , 200 m, 3–23 December 1999, secondary forest with primary spots, Winkler extraction, leg. A. Schulz ( MHNG, AS–T–5) . 2♂, 1♀, Nakhon Ratchasima Province, Khao Yai National Park, Khao Khiew , evergreen hill forest, 1150 m, 29 October 1997, leg. P.J. Schwendinger ( MHNG, 7) .

Diagnosis

Males of S. minuatus sp. nov. are recognized by the presence of a rectangular projection on the apex of the proximal RTA ( Figures 3 L, 5 A,C), in combination with the medially situated conductor. Males are distinguished from their congeners by the minute distal RTA ( Figures 3 L, 5 C). Females can be distinguished from those of the closely related S. emancipatus sp. nov. by the longer grooves on the epigynal region ( Figures 5 D cf. 10 E), the more elongated and strongly arched proximal ducts in dorsal view ( Figure 5E ).

Etymology

The specific epithet is a Latinized adjective referring to a small, sharply pointed distal RTA of the male palp.

Description

Male (holotype). Total length 5.20; prosoma 2.60 long, 1.82 wide; opisthosoma 2.86 long, 1.62 wide. Leg measurements: leg I 7.14 (1.94, 2.60, 1.48, 1.10); II 6.10 (1.62, 2.20, 1.30, 0.98); III 5.16 (1.48, 1.46, 1.30, 0.90); IV 7.92 (2.08, 2.48, 2.20, 1.16). Leg spination. Leg I: Fe p–1, Ti v–2–2 –2–2–2–2–2, Mt v–2–2 –2–2; leg II: Ti v–2–2 –2–2– 2–2, Mt v–2–2 –2–2; leg III: Ti p–1–1 v–1–1 –1–1 r–1, Mt p–1 v–1–1 –1 r–1; leg IV: Fe d–1, Ti p–1–1 v–1–1 –1 r–1, Mt p–1, v–1–1, r–1–1.

Pattern and coloration ( Figure 1 C). Carapace dark reddish brown, sparsely clothed with white pubescence; integument granulated, nodules minute, evenly distributed, few or less on pars cephalica; chelicerae, labium and gnathocoxae dark reddish brown; sternum brown; legs bicolored, coxae to femora orange-brown, patellae to tarsi yellow, white annulation present on distal half of anterior tibiae. Opisthosoma elongateovoid; venter pale, with two longitudinal rows of heavily sclerotized, circular spots; epigastric scutum dark reddish brown, heavily sclerotized, protruding anteriorly, forming grooved collar; dorsal scutum heavily sclerotized, reddish brown, occupying entire length of opisthosoma, sparsely covered with white pubescence.

Palp ( Figures 3 L, 5 A–C). Palpal tibia with digitiform prolateral excrescence; proximal RTA with membranous anterior surface, posterior surface heavily sclerotized, apex provided with semi-transparent, quadrangular projection; distal RTA minute, sharply pointed; tegulum strongly excavated apico-prolaterally, with distinctly elevated anterior portion; conductor lanceolated, originating medially, sides paralleled in ventral view; tegular apophysis originating posterior to base of conductor.

Female (paratype, MHNG). Total length 6.16; prosoma 3.08 long, 2.16 wide; opisthosoma 3.50 long, 1.92 wide. Leg measurements: leg I 8.46 (2.30, 3.08, 1.78, 1.30); II 7.23 (1.92, 2.60, 1.54,1.16); III 6.12 (1.78, 1.74, 1.54, 1.08); IV 9.38 (2.46, 2.90, 2.60, 1.30). Leg spination. Leg I: Fe p–1, Ti v–2–2 –2–2–2–2–2, Mt pv–1 v–2–2 –2–2; leg II: Ti v–2–2 –2–2–2, Mt v–2–2 –2–2; leg III: Ti p–1–1 v–1–2 –1 r–1, Mt p–1 v–1–2 r–1; leg IV: Fe d–1, Ti p–1–1 v–1–1 –2 r–1, Mt p–1, v–2–1, r–1.

Pattern and coloration ( Figure 1D ). Carapace dark reddish brown, clothed with short, white pubescence; integument coarsely granulated, unevenly distributed on carapace, more on peripheral margin; chelicerae, labium and gnathocoxae brown; sternum dark brown; legs orange-brown except anterior femora and tibiae brown; green annulation present on distal half of anterior tibiae. Opisthosoma ovoid; dorsum dark grey, posteriorly with series of pale chevrons; venter pale, without pattern; dorsal scutum heavily sclerotized, ovoid, orange-brown, occupying four-fifths length of opisthosoma; epigastric scutum heavily sclerotized, protruding anteriorly, forming ring collar.

Genitalia ( Figures 5D–F ). Epigastric scutum with pair of semi-circular copulatory orifices connected to narrowed, longitudinal grooves; proximal ducts broad, strongly arched; insemination ducts intertwined, forming five or six coils in mid-longitudinal axis; spermathecae elliptical, with large, circular gland pores situated anteriorly.

Natural history

Males of this new species clearly mimic ants. Their opisthosoma is entirely encapsulated with an elongate-ovoid dorsal scutum, which is clothed with white hairs and underlying dark greyish dorsal pattern. Together with a stalk-like pedicel, they give an appearance of a segmented abdomen of the ants. The presence of rows of short, straight bristles on dorsal and ventral surface of leg segments also give an impression of the setae in ants.

Distribution

Eastern Thailand.

Figures

Figure 1. Sesieutes spp., dorsal habitus (A – O). Sesieutes lucens Simon, male (A), female (B). Sesieutes minuatus sp. nov., holotype male (C), paratype female (D). Sesieutes abruptus sp. nov., holotype male (E), paratype female (F). Sesieutes bifidus sp. nov., holotype male (G), paratype female (H). Sesieutes apiculatus sp. nov., holotype male (I), paratype female (J). Sesieutes aberrans sp. nov., holotype male (K). Sesieutes sp. from Vietnam, male (L). Sesieutes sp. from Laos, male (M). Sesieutes borneensis Deeleman-Reinhold, male from Palawan (N). Sesieutes sp. from southern Thailand, female (O). Scale bar 1. 0 mm.

Figure 2. Sesieutes spp. Sesieutes lucens Simon, male, prosoma, ventral view (A); S. lucens Simon, male, ocular region, dorsal view (B); Sesieutes minuatus sp. nov., paratype male, fovea, dorsal view (C); Sesieutes sp., male from Vietnam, fovea, dorsal view (D). Scale bar 0. 2 5 mm.

Figure 3. Sesieutes spp., male palp, retrolateral view (A – C, G, I – L), ventral view (D, E), dorsal view (F, H). Sesieutes bulbosus Deeleman-Reinhold, holotype (A); Sesieutes borneensis Deeleman-Reinhold, holotype (B); Sesieutes apiculatus sp. nov., holotype (C); Sesieutes lucens Simon, holotype (D); Sesieutes abruptus sp. nov., holotype (E, F); Sesieutes scrobiculatus Deeleman-Reinhold, holotype (G, H); Sesieutes aberrans sp. nov., holotype (I); Sesieutes nitens Deeleman-Reinhold, holotype (J); Sesieutes emancipatus Deeleman-Reinhold, holotype (K); Sesieutes minuatus sp. nov., holotype (L). Scale bar 0. 1 mm.

Figure 5. Sesieutes minuatus sp. nov. Holotype, male palp (A – C), ventral view (A), prolateral view (B), retrolateral view (C). Paratype, female (D – F), epigyne, ventral view (D); internal genitalia, dorsal view (E); right spermatheca and proximal duct, ventral view (F). Scale bars 0. 1 mm (A – C); 0. 2 5 mm (D – F).