Hesperochthonius Muchmore, 1968 n

Zaragoza, Juan A., 2017, Revision of the Ephippiochthonius complex in the Iberian Peninsula, Balearic Islands and Macaronesia, with proposed changes to the status of the Chthonius subgenera (Pseudoscorpiones, Chthoniidae), Zootaxa 4246 (1), pp. 1-221 : 22-23

Genus Hesperochthonius Muchmore, 1968 n . stat.

Diagnosis. Genus of the tribe Chthoniini with lagyniform chela (sensu Judson 2007), the chelal hand resembling in part the ephippiochthonian form, with variable dorsum outline, having an abrupt to flattened hump distad of trichobothria ib / isb and an abrupt to gentle depression towards the fixed finger base ( Fig. 21 ); without ventral hollow before base of movable finger; base of chelal hand gently constricted paraxially; without a medial protuberance (ip) between chelal condyles. Proximal portion of chelal hand with 4 setae in adults, seta ph3 present. Pedipalpal fingers of about the same length; dental rows homodentate, both fingers bearing spaced, upright teeth ( Chamberlin 1929a, 1949; Muchmore 1968) or contiguous trapezoidal teeth in distal half followed by a row of contiguous, rounded teeth in basal half ( Schuster 1962); subdistal tooth (mt) of fixed finger not modified; tip of fixed finger with an accessory tooth (td) on antiaxial face (rounded and weakly hyaline, at least in H. californicus ; apparently absent in H. spingolus ); tip of fixed chelal finger of male without a deep hollow on paraxial face and subapical protuberance (sp); base of movable chelal finger with a weakly enlarged condyle and proximally with a sclerotized, short and strong ( H. spingolus ) or medium-sized and thin apodeme [ H. californicus and, apparently, H. oregonicus ( Muchmore, 1968) ]. Lyrifissure ma1 present, ma2 absent. Anterior margin of carapace more strongly dentate between median macrosetae, weakly prominent, without epistome. Coxae II and III with coxal spines; bisetose intercoxal tubercle present between coxae III and IV; distal marginal seta of pedipalpal coxa disk distinctly longer than the distal marginal seta of coxa I; sternite III of males and females usually with 10 marginal setae, of which the lateral one on each side is short ( Fig. 22 ). Male genitalia with each row of glandular setae (guard-setae) divided by a median hiatus into two groups of two setae ( Fig. 23 ).

Type species. Chthonius californicus Chamberlin, 1929 .

Distribution. North America: U.S.A.

Remarks. The subgenus Hesperochthonius was created by Muchmore (1968), based on the species Chthonius californicus (Chamberlin, 1929) , for which the main differential characteristic relative to the other Chthonius - related genera is the presence of a hiatus between each row of the internal guard setae of the male genitalia, forming two groups of two setae on each side, which appears to be unique within the Chthoniidae . In addition to H. californicus , two other species, also from U.S.A., are currently assigned to Hesperochthonius .

Examination during this study of the male holotype, the female paratype (“ allotype ”) ( Chamberlin 1929a, 1949) and the female (JC-323.01001) described by Chamberlin (1929b, 1949) of Hesperochthonius californicus (Chamberlin, 1929) , type species of the genus, and of the male holotype of H. spingolus ( Schuster, 1962) , confirm the main characteristics of the genus established by Muchmore (1968) and the assignment to that genus of H. spingolus , suggested by Judson (1990a), based on Schuster’s (1962) description and figures of a median hiatus in the rows of the genital guard-setae, and later formalized by Harvey (1991). In addition to the different shape of the teeth of the distal half of the chelal fingers and the fixed chelal finger apodeme in the two species, the close guard setae of each group have their external areoles partially fused in H. californicus ( Fig. 23 ), whereas in H. spingolus they are very close together but still in separate external areolar rings. An additional difference from the genus Ephippiochthonius is the chaetotaxy of the proximal portion of chelal hand, which bears 4 setae in Hesperochthonius and only 3 in Ephippiochthonius (ph 3 absent).

Figures

FIGURES 21 – 23. Hesperochthonius californicus (Chamberlin, 1929) n. comb., male holotype, California, U. S. A. 21, right chela, antiaxial view, slightly dorsal; 22, external genital area; 23, internal genital area. See Material and methods for abbreviations.