Jacaena Thorell, 1897

Dankittipakul, Pakawin, Tavano, Maria & Singtripop, Tippawan, 2013, Revision of the spider genus Jacaena Thorell, 1897, with descriptions of four new species from Thailand (Araneae: Corinnidae), Journal of Natural History 47 (23), pp. 1539-1567 : 1543-1549

publication ID	https://doi.org/ 10.1080/00222933.2012.763059
persistent identifier	https://treatment.plazi.org/id/EC2A175A-FFB1-FF8F-AFB8-D66DFBC09DBC
treatment provided by	Jeremy
scientific name	Jacaena Thorell, 1897
status

Treatment

Genus Jacaena Thorell, 1897 View in CoL

Jacaena Thorell, 1897: 230 View in CoL ; Deeleman-Reinhold, 2001: 465 Type species

Jacaena distincta Thorell, 1897 View in CoL Diagnosis

Representatives of Jacaena can be recognized by a combined presence of characters: the integument of carapace is strongly granulate or punctate, forming radiating striae ( Figures 1–2 View Figure 1 View Figure 2 ); the fovea is deep and circular ( Figure 3 View Figure 3 B); the dorsal opisthosomal scutum occupying approximately half the length of the opisthosoma or much less in males ( Figure 1 View Figure 1 ), completely absent in females ( Figure 2 View Figure 2 ); the dorsal pattern of the opisthosoma consists of paired, oval patches, followed by three to five pale chevrons ( Figures 1–2 View Figure 1 View Figure 2 ) on a dark greenish background; the male palp is provided with an apically excavated proximal RTA and a truncated distal RTA ( Figure 12 View Figure 12 A); the pyriform tegulum bears a distal conductor and a hyaline tegular apophysis ( Figure 9 View Figure 9 D); the embolic base originates disto-prolaterally, its filiform embolus wrapping behind the tegulum ( Figure 4 View Figure 4 C, D); the elongated female internal ducts are coiled, moving peripherally before leading to poorly defined or elliptical spermathecae, which are posteriorly situated.

Description

Carapace ( Figures 1 View Figure 1 , 2 View Figure 2 ) ovoid in dorsal view, attenuated in front, narrowed opposite palpal insertion, widest between coxae II and III, in profile highest between PME and fovea; pars thoracica rounded, marked with deep, circular fovea ( Figure 3 View Figure 3 B); ocular area and clypeus with few stiff setae; pars thoracica with fine recumbent setae; integument of carapace usually with numerous granules ( Figures 1 View Figure 1 A–B, D–H, 2A–E, G–H) or punctures ( Figures 1 View Figure 1 C, 2F) forming radiating striae; colour from dark chestnutbrown to brownish orange. Both eye rows straight in dorsal view ( Figures 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 D); in frontal view, AER very slightly procurved, PER slightly procurved ( Figure 3 View Figure 3 E); AME circular, dark; PME oval, pearly white; ALE and PLE subcircular, light; anterior eyes separated by their diameter or less; posterior eyes evenly spaced, separated by 1.5–2 their diameter (except in J. mihun comb. nov. and J. thakek comb. nov. whose PME are distinctly enlarged); ALE and PLE separated by 1–1.5 times their diameter. MOQ longer than wide, slightly wider in front than behind (wider behind than in front in J. mihun comb. nov. and J. thakek comb. nov. because of enlarged PME). Clypeal height 1.5 times diameter of AME. Chelicerae convex anteriorly, with conspicuous condyles, fang furrow with three promarginal teeth and one to three retromarginal denticles. Chilum heavily sclerotised, trapezoidal ( Figure 3 View Figure 3 E). Mouthparts and sternum brownish orange, darker along sternal margin. Labium ( Figure 3 View Figure 3 A) subtriangular, longer than wide, invaginated at posterolateral corners, with few strong setae on anterior surface. Gnathocoxae ( Figure 3 View Figure 3 A) rectangular, with very faint oblique depressions, each with anterolateral serrula and anteromedian scopula arising from pale apical area. Sternum ( Figure 3 View Figure 3 A) scutiform, strongly rebordered, posterior margin truncated, not protruded between coxae IV; anterior margin medially excavated to accommodate labium; lateral margin with triangular extensions fitting to and between coxae. Leg formula 4123; legs brownish orange; femora I always with two elongated disto-prolateral spines; patellae unmodified; anterior tibiae ventrally not flattened, with five to nine pairs of ventral spines and single prolateral spine; anterior metatarsi with four to six pairs of ventral spines; posterior metatarsi with brush of distoventral hairs, anterior without such brush; anterior tarsi devoid of spines; posterior tarsi with few spines; two pectinate claws carrying two to three denticles; claw tufts indistinct; trichobothria long, in two dorsal rows on tarsi and metatarsi, one row on tibiae increasing in length distally.

Opisthosoma ( Figures 1 View Figure 1 , 2 View Figure 2 ) ovoid in dorsal view, dark greenish dorsally, dorsal pattern consisting of two pale oval patches situated medially, followed by three to five chevrons. Dorsal scutum with poorly diffused edge, covering less than half the length of the opisthosoma in male, completely absent in female. Two pairs of muscle apodemes, their surface covered by minute, circular, heavily sclerotised spots; first pair of spots locating just behind dorsal scutum ( Figures 1 View Figure 1 , 2 View Figure 2 ), second pair always located at centre of second pale oval patches. Epigastric region entirely covered with scutum ( Figure 3 View Figure 3 C), slightly extending anteriorly to form short collar. Ventral scutum absent. Postgenital scuta ( Figure 3 View Figure 3 C) triangular or semi-circular, situated posterior laterally, surrounding book lung openings but clearly separated from epigastric scutum. Colour of venter uniform in all species ( Figure 3 View Figure 3 C), dark greenish, marked with dark trident on pale rectangular area, with numerous tiny sclerotised spots arranged into four longitudinal lines running between epigastric furrow and transverse tracheal spiracle. Spinnerets two-segmented; ALS conical, contiguous, distal segment short; PMS small, slender in males, flattened and elongated in females; PLS with short distal segment.

Male palp. Palpal femur without modification. Retrolateral tibial apophysis consisting of basal and distal parts ( Figure 12 View Figure 12 A); basal RTA triangular or digitiform, apical surface usually with deep excavation; distal RTA short and membranous, digitiform. Cymbium dorsally with mid-longitudinal patch of chemosensitive hairs ( Figure 4 View Figure 4 B, E, H). Tegulum elongate-ovoid, with distinct apico-prolateral depression accommodating base of embolus. Embolus filiform, elongated, curving behind tegulum ( Figure 4 View Figure 4 A, B). Tegular apophysis hyaline, gradually tapered, originating near base of conductor ( Figures 6 View Figure 6 A, 9 D). Conductor originating on disto-prolateral surface of tegulum; its shape from simple, triangular projection ( Figure 10 View Figure 10 A, D) to elongated cylinder with median groove ( Figures 5 View Figure 5 D, 13A) or large crescent-shaped lamina ( Figures 6 View Figure 6 A, 9 D).

Female copulatory organ. Epigynal region ( Figure 7 View Figure 7 ) heavily sclerotised, with two copulatory orifices usually filled with dark secretory substance ( Figure 7 View Figure 7 A, B). Internal duct system consisting of semi-transparent proximal duct ( Figures 6 View Figure 6 F, 14 C) or enlarged chamber ( Figures 6 View Figure 6 D, 13 E) connected to loosely coiled insemination ducts ( Figure 12 View Figure 12 E: ID) and spermathecae. Spermathecae slightly enlarged, poorly defined ( Figure 8 View Figure 8 A–D, G) or with elliptical and spherical enlargement ( Figure 8 View Figure 8 E, F); surface of spermathecae usually provided with glandular pores ( Figures 8 View Figure 8 G, 12 E). Small, perforated ampulla ( Figures 6 View Figure 6 D, F, 12 E, 13 E, 14 B, E: AM) connected to proximal portion of insemination ducts or chambers ( Figures 6 View Figure 6 D, 13 E), usually with hardened secretion filling proximal portion of ducts ( Figure 7 View Figure 7 A, B).

Natural history

Most Jacaena species were collected by sifting decomposing organic litter in moist, primary evergreen hill forests at relatively high elevation. These forests are generally covered with a thick layer of humus on the forest floor and the forest canopy is often dense, allowing limited sunlight to reach the ground. A species from Thailand ( J. mihun ) inhabits deciduous forests and open plantations. Jacaena thakek was sifted from relatively dry litter in a narrow belt of trees, bamboo or Rattan (disturbed secondary habitat); the type locality of this species is almost of the same altitude of the Mekong basin (159 m alt.)

Included species

Jacaena angoonae sp. nov.; J. distincta Thorell, 1897 ; J. erawan (Deeleman-Reinhold, 2001) comb. nov.; J. lunulata sp. nov.; J. mihun Deeleman-Reinhold, 2001 ; J. punctata sp. nov.; J. peculiaris sp. nov.; J. schwendingeri (Deeleman-Reinhold, 2001) comb. nov.; J. thakek (Jäger, 2007) comb. nov.; J. zhui (Zhang and Fu, 2011) comb. nov. Two further species were also collected from Vietnam (male and female) and China (female); they have not yet been described.

Distribution

Predominantly Indo-Burmese sub-region of the Oriental Region (Myanmar, Thailand, Laos, Vietnam), also in evergreen forests of southern China (Yunnan Province).