Chaerilus majkusi, Kovařík & Lowe & Šťáhlavský, 2018

Kovařík, František, Lowe, Graeme & Šťáhlavský, František, 2018, Three new Chaerilus from Malaysia (Tioman Island) and Thailand (Scorpiones Chaerilidae) with a review of C cimrmani C sejnai and C tichyi, Euscorpius 268, pp. 1-27 : 2-7

Chaerilus majkusi sp. n.

( Figs. 1–34, 37, 39–40, 43, 109, 115–116, Table 1) http://zoobank.org/urn:lsid:zoobank.org:act:CFDA

1E06-D868-4A5E-ACB2-7A51F1690BA7

TYPE LOCALITY AND TYPE REPOSITORY. Malaysia, Pahang, Tioman Island, Kampung Genting , tropical forest, 02°45'57"N 104°07'48"E 45 m a.s.l. , FKCP.

TYPE MATERIAL. Malaysia, Pahang, Tioman Island, Kampung Genting , tropical forest, 02°45'57"N 104° 07'48"E 45 m a.s.l. ( Fig. 43), 7. IX.2016, 1♂ (holotype, 1278) 3♂ 2♀ 1♂ juv (paratypes), leg. D. Ho-ferek & R. Majkus , 3♂ 2♀ 8 juvs. (paratypes, 1454–1456, offspring of the female paratype, some of them still alive), bred by D. Hoferek and F. Kovařík , FKCP.

ETYMOLOGY. A patronym in honor of Zdeněk Majkus, Czech Republic, for his friendship and lifelong dedication to arachnids.

DIAGNOSIS. Total length 25–29 mm. Two pairs of lateral eyes and one pair of median eyes. Male differs from female in having pedipalp chela much wider. Chela length/width ratio in male 1.87; in female 2.28. Movable finger of pedipalp with 16 imbricated granule rows. Fingers straight in both sexes. Chela of pedipalp with 7–8 carinae. Pectinal teeth number 6 in males, 4 in females. Carapace granulated. Mesosomal tergites granulated mainly in median area. All sternites smooth without carinae and granules. First metasomal segment with 6 or 8 carinae, second to fourth segments with 6 carinae, ventral metasomal carinae absent. All metasomal segments very sparsely granulated.

DESCRIPTION. Total length 25–29 mm. Two well developed pairs of lateral eyes and one pair of median eyes

( Figs. 5–6). The chelicerae ( Figs. 33–34) are smooth, yellow and strongly reticulate, anteriorly black. The male differs from the female in having pedipalp chela much wider with short fingers. The chela length/width ratio in the male 1.87; in the female 2.28. The male has relatively larger pectines ( Figs. 7 and 8). There is no sexual dimorphism in shape of metasoma and telson. For the position and distribution of trichobothria, see Figs. 25–31. For measurements, see Table 1.

COLORATION ( Figs. 1–4). The color is yellowish orange to brown, spotted. Older specimens are darker (see Fig. 39 versus 40).

CARAPACE AND MESOSOMA ( Figs. 5–8). The carapace is covered by large granules that do not form carinae and are absent from two strips in the median area. The anterior margin of the carapace is almost straight to weakly concave. The mesosomal tergites are irregularly granulated. All sternites are smooth without carinae and granulation. Sternite V with smooth patch indicated. Pectinal teeth number 6 in males, 4 in females.

METASOMA AND TELSON ( Figs. 13–20). The first metasomal segment bears 6 or 8 incomplete carinae, the second to fourth bear six incomplete carinae, and the fifth segment bears four carinae. All carinae are composed of sparse, large granules. The spaces between carinae are very sparsely, irregularly granulated, more so on lateral surfaces of all segments and ventral surfaces of segments IV–V. Metasomal segments I–III are ventrally smooth without carinae and granules. All segments are very sparsely hirsute. The telson is elongate, smooth and very sparsely hirsute.

PEDIPALPS ( Figs. 21–32). The pedipalp chela is stout with swollen manus in the male. The movable finger bears 16 and the fixed finger 15 imbricated rows of granules. The chela has seven or eight mostly granulated carinae. The carina on the externodorsal surface of the manus may be incomplete. The dorsal and internal surfaces of chela with reticulate granulation patterns. The patella is smooth with dorsal carina developed and granulated, other carinae are absent or weakly indicated. The femur has four carinae.

LEGS ( Figs. 9–12). The legs are sparsely hirsute, without bristlecombs and carinae. The femora and patellae are granulated dorsally, with other surfaces smooth. The tarsomeres bear four rows of spiniform setae. Spiniform setal formula of inner rows is 7–8/7–8: 10– 12/10–11: 9–12/9–11: 10–11/10–12; of outer rows is 5– 8/5–8 on all legs.

HEMISPERMATOPHORE ( Fig. 109). Fusiform, with relatively large capsule region (ca. 650 µm), and relatively short distal lamina (ca. 370 µm) angled posteriorly and apically truncated. Sperm hemiduct of capsule weakly sclerotized, with long posterior carina and shorter anterior carina.

KARYOTYPE ( Figs. 115–116). We analyzed the karyotypes of the male holotype and the three male paratypes. The diploid complement of all specimens is 76 chromosomes ( Fig. 115). The chromosomes are small and their morphology is not clearly visible during mitotic metaphase. However, the conspicuous constrictions on chromosomes during postpachytene and metaphase I indicate the existence and predominance of bi-armed chromosomes in this species ( Fig. 116). The chromosomes gradually decrease in length from 3.38% to 1.65% of the haploid set. We did not identify any heteromorphic bivalent during postpachytene and metaphase I, and we did not observe chiasmata during these phases.

A FFINITIES. Chaerilus majkusi sp. n. is reliably distinguished from all other Chaerilus species by the following unique combination of characters: total length 25–29 mm; movable fingers of pedipalp with 16 rows of granules; pedipalp chela wide, stout with swollen manus in the male; pedipalp fingers straight in both sexes; metasomal segments I–III ventrally smooth without carinae and granules; tarsomeres of legs bear four rows of spiniform setae.

Chaerilus majkusi sp. n. is the third Chaerilus species recorded from Tioman Island. This island is of special interest because it is inhabited both by Chaerilus tichyi Kovařík, 2000 ( Figs. 41–42), the largest known member of the family Chaerilidae (70–80 mm), and by Chaerilus sejnai Kovařík, 2005 ( Figs. 38) which may be smallest known member of the family (16–22 mm) if we exclude species that were described from juveniles ( Chaerilus kampuchea Lourenço, 2012 and Chaerilus sabinae Lourenço, 1995 ).