Chaerilus pulcherrimus sp. n.

(Figures 51–83, 85–86, Table 1)

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TYPE LOCALITY AND TYPE REPOSITORY. Laos, Champasak Province, FKCP.

TYPE MATERIAL (FKCP). Laos, Champasak Province, 5.VIII.2019, 1♂ (holotYpe, 1852, Figs. 51–55, 57–71, 80– 83), 1♀ (paratYpe, damaged, Figs. 56, 72–79, scorpion born 15.VIII.2020), leg. V. Fura, 14 juvs. (paratYpes, offspring of the female paratYpe 15.VIII.2020, 2 nd ecdYsis 21.IX.2020, 3 rd ecdYsis 20.X.2020, still alive), bred bY F. Kovařík.

ETYMOLOGY. The specific epithet is derived from the Latin nominative, singular adjective pulcherrimus (masculine), a superlative of pulcher = beautiful, in reference to the colorful maculose patterns on the carapace, tergites, metasoma and telson of this diminutive species.

DIAGNOSIS (♂ ♀). Total length 16–19 mm; two pairs of lateral eYes and one pair of median eYes; ventral surface of cheliceral fixed finger with 4 denticles; chela length/width ratio ♂ 2.57, ♀ 2.69; movable pedipalp finger with 8 imbricated granule rows; fingers straight in both sexes; pedipalp chela with 7 carinae; pectinal tooth count ♂ 4, ♀ 3; carapace and mesosoma granulated in both sexes; all sternites smooth without carinae and granules; metasoma I–IV with 6 or 8 carinae, ventral carinae reduced or absent.

DESCRIPTION. Total length ♂ 18.8 mm, ♀ 16.4 mm; color reddish orange to brown, maculose; chelicerae sparselY finelY granulated dorsallY, Yellow and stronglY reticulate, anteriorlY black; male differs from female in having pedipalp chela slightlY narrower with short fingers; chela length/width ratio ♂ 2.57, ♀ 2.69; male with larger pectines; no sexual dimorphism in shape of metasoma and telson; trichobothrial pattern as shown in Figs. 63–69, measurements in Table 1.

Carapace and mesosoma (Figs. 54–55). Carapace covered bY large granules in both sexes; anterior margin of carapace almost straight; two well developed pairs of lateral eYes and one pair of median eYes present; mesosomal tergites irregularlY granulated, mainlY on tergite VII; all sternites smooth without carinae and granulation; sternite V with smooth patch indicated; pectinal tooth count ♂ 4, ♀ 3.

Metasoma and telson (Figs. 56–60). Metasoma I–IV with 6 or 8 incomplete carinae, ventral carinae reduced to absent, dorsal carinae are composed of strong denticles; metasoma V with 5 carinae; intercarinal surfaces sparselY, irregularlY granulated, more so on lateral surfaces of all segments and ventral surfaces of segment V; all segments verY sparselY hirsute; telson elongate, ampullate, smooth, verY sparselY hirsute.

Pedipalps (Figs. 63–79). Pedipalp chela rather stout with swollen manus mainlY in female; movable finger with 8 and fixed finger with 7 imbricated rows of granules; chela with 7 carinae, smooth in both sexes; dorsal and internal surfaces of chela with reticulate granulation patterns; patella with 4–5 smooth, reduced carinae, or carinae absent; surfaces of patella smooth except for internal surface which is sparselY granulated; femur denselY granulated with four incomplete carinae.

Legs (Figs. 61–62). Hirsute, without bristlecombs and carinae; femora and patellae smooth; tarsomeres with two rows of spiniform setae; spiniform seta formula 5–6/5–7: 6–7/6–7: 7–8/7–8: 7–8/7–9.

Hemispermatophore (Figs. 80–83). Fusiform; distal lamina short, broad, weaklY tapered, apex rounded; capsule with distal carina weaklY sclerotized; sperm hemiduct delineated bY two thin, sclerotized carinae, of which the distal is longer, the basal shorter; capsule elongate, ca. 50% longer than distal lamina; trunk long, as broad as capsule. Measurements of left hemispermatophore (mm): distal lamina length 0.35, capsule length 0.53, trunk length 1.10, pedicel length 0.22, capsule width 0.30. Right hemispermatophore similar to the left hemispermatophore.

Karyotype (Figs. 85–86). Male holotYpe was analYzed. The diploid complement is 102 chromosomes in the mitotic metaphases (Fig. 85). During metaphase I, 51 bivalents were observed (Fig. 86), implYing that 2n=102. Chiasmata were not observed during meiosis.

AFFINITIES. The described features distinguish C. pulcherrimus sp. n. from all other species of the genus. C. pulcherrimus sp. n. is similar to C. celebensis Pocock, 1894 (see keY in Kovařík & Ojanguren, 2013: 131–133). These two species can be differentiated bY pedipalp chela granulation. The chela has smooth carinae in C. pulcherrimus sp. n. (Fig. 63) vs. granulated carinae in C. celebensis (fig. 42 in Kovařík, 2019: 8).

C. pulcherrimus sp. n. is reliablY distinguished from all other Chaerilus species bY the following unique combination of four characters: movable finger of pedipalp with 8 imbricated granule rows; total length 16–19 mm; pedipalp chela length/ width ratio ♂ 2.57, ♀ 2.69; and sternite VII smooth.

OnlY one other species of the genus was reported from Laos: C. laoticus Lourenço & Zhu, 2008. This species differs in having the male pedipalp chela verY narrow, with length/ width ratio 4.0–4.2.