Chaerilus Simon, 1877

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

Chaerilus Simon, 1877

( Figs.1–125, Table 1)

Chaerilus Simon, 1877: 238 ; Kovařík & Ojanguren, 2013: 131–145, figs. 617–776 (complete reference list until 2013); Kovařík et al, 2015: 1–21, figs. 1– 91, tables 1–3.

= Chelomachus Thorell, 1889: 583 (syn. by Kraepelin, 1899: 157).

= Uromachus Pocock, 1890: 250 (syn. by Kraepelin, 1899: 157).

TYPE SPECIES. Chaerilus variegatus Simon, 1877 .

DIAGNOSIS. Total length 16–80 mm; orthobothriotaxy type B; pedipalp femoral d 3 –d 4 trichobothria configuration points toward dorsoexternal carina; pedipalp patella with three ventral trichobothria and pedipalp femur with 9 trichobothria, 4 of them dorsal; cheliceral fixed finger with median and basal denticles flush on surface, not fused into bicusp; ventral edge of cheliceral movable finger crenulated, dorsal edge with single subdistal denticle; ventral surface of cheliceral fixed finger with four denticles; dorsal edge of cheliceral movable finger with a single subdistal denticle; ventral surface of cheliceral fixed finger with denticles; sternum, type 1, exhibits subtle wide horizontal compression; maxillary lobes I spatulate; hemispermatophore is fusiform; median denticle row (MD) of pedipalp chela finger arranged in oblique groups; pedipalp chela exhibits "8-carina" configuration; legs without tibial spurs, but with prolateral and retrolateral pedal spurs; tarsi of legs bear two or four rows of ventral setae and median row of spinules; fifth metasomal segment with a single ventral carina; telson without subaculear tubercle.

CYTOGENETICS. Our cytogenetic analyses of six Chaerilus species confirmed the basic cytogenetic characteristics of the family Chaerilidae that are shared with other scorpions. Typical for this arachnid order are the absence of morphologically differentiated sex chromosomes and achiasmatic meiosis in males (e. g. Schneider et al., 2009). Moreover, we found a great range of variation in the diploid number within Chaerilidae (2n=76–186) that is similar to the variation in several other better characterized families with monocentric chromosomes such as Hormuridae (2n= 54–174), Scorpionidae (2n=50–120), and Urodacidae (2n=29–175) (Schneider et al., 2018). Interestingly, Chaerilus stockmannorum sp. n. has the highest known number of chromosomes (2n=186) within the order Scorpiones . The different karyotype characteristics among Chaerilus species again emphasize the importance of cytogenetic analysis in the taxonomy of scorpions as was already demonstrated in genera Heterometrus (Scorpionidae) ( Plíšková et al., 2016) and Hadogenes (Hormuridae) ( Šťáhlavský et al., 2018).

HEMISPERMATOPHORES. The chaerilid hemispermatophores documented here are similar to those previously reported for the family ( Bastawade, 1994; Kovařík et al., 2015; Lourenço & Duhem, 2010; Monod et al, 2017; Stockwell, 1989). All conform to the basic plan of a laterally compressed fusiform structure with relatively large capsule region, relatively short, broad trunk, and a short, posteriorly directed distal lamina. The sperm hemiduct of the capsule is reinforced by a longer, stronger posterior (distal) carina, and a shorter, weaker anterior (basal) carina. As seen in Figs 108– 114, the form of the capsule region is well conserved across a variety of species, lacking variation that might provide taxonomically useful characters. Although there appear to be interspecific differences in size and shape of the distal lamina, an example of two individuals of Chaerilus hofereki ( Figs. 113–114) shows that there can also be large intraspecific differences. Determination of diagnostic interspecific differences, if they exist, will require statistical analysis of morphometrics and shapes of a much larger sample of hemispermatophores from each species.