Genus Jacaena Thorell, 1897

Jacaena Thorell, 1897: 230; Deeleman-Reinhold, 2001: 465

Type species

Jacaena distincta Thorell, 1897

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); the fovea is deep and circular (Figure 3B); the dorsal opisthosomal scutum occupying approximately half the length of the opisthosoma or much less in males (Figure 1), completely absent in females (Figure 2); the dorsal pattern of the opisthosoma consists of paired, oval patches, followed by three to five pale chevrons (Figures 1–2) on a dark greenish background; the male palp is provided with an apically excavated proximal RTA and a truncated distal RTA (Figure 12A); the pyriform tegulum bears a distal conductor and a hyaline tegular apophysis (Figure 9D); the embolic base originates disto-prolaterally, its filiform embolus wrapping behind the tegulum (Figure 4C, 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, 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 3B); ocular area and clypeus with few stiff setae; pars thoracica with fine recumbent setae; integument of carapace usually with numerous granules (Figures 1A–B, D–H, 2A–E, G–H) or punctures (Figures 1C, 2F) forming radiating striae; colour from dark chestnutbrown to brownish orange. Both eye rows straight in dorsal view (Figures 1, 2, 3D); in frontal view, AER very slightly procurved, PER slightly procurved (Figure 3E); 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 3E). Mouthparts and sternum brownish orange, darker along sternal margin. Labium (Figure 3A) subtriangular, longer than wide, invaginated at posterolateral corners, with few strong setae on anterior surface. Gnathocoxae (Figure 3A) rectangular, with very faint oblique depressions, each with anterolateral serrula and anteromedian scopula arising from pale apical area. Sternum (Figure 3A) 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, 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, 2), second pair always located at centre of second pale oval patches. Epigastric region entirely covered with scutum (Figure 3C), slightly extending anteriorly to form short collar. Ventral scutum absent. Postgenital scuta (Figure 3C) 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 3C), 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 12A); 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 4B, E, H). Tegulum elongate-ovoid, with distinct apico-prolateral depression accommodating base of embolus. Embolus filiform, elongated, curving behind tegulum (Figure 4A, B). Tegular apophysis hyaline, gradually tapered, originating near base of conductor (Figures 6A, 9D). Conductor originating on disto-prolateral surface of tegulum; its shape from simple, triangular projection (Figure 10A, D) to elongated cylinder with median groove (Figures 5D, 13A) or large crescent-shaped lamina (Figures 6A, 9D).

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