Heurtaultia, Judson, 2009

Judson, Mark L. I., 2009, Cheliferoid pseudoscorpions (Arachnida, Chelonethi) from the Lower Cretaceous of France, Geodiversitas 31 (1), pp. 61-71 : 63-64

Genus Heurtaultia n. gen.

TYPE SPECIES. — Heurtaultia rossiorum n. sp.

ETYMOLOGY. — The genus is dedicated to the late Jacqueline Heurtault, a dear friend and colleague who made many important contributions to our knowledge of extant French pseudoscorpions; gender feminine.

DIAGNOSIS. — Mesozoic Cheliferoidea with elongate body. Setae generally small and dentate, not on raised tubercles. Granulation dense, even and low. Carapace much longer than broad; median furrow weakly marked, posterior furrow either weak or absent; one pair of large eyes with moderate lenses. Palp trochanter large, without lobes. Chelal fingers strongly gaping in male when closed. Trichobothrium it near middle of finger. Teeth of chela long, upright and cusped; accessory teeth absent. Joint between femur and patella of anterior legs moderately oblique, femur only slightly broader than patella. Coxa IV of male without lateral spur and posterior margin not excavated; probably without coxal sac. Leg I with elongate setae on tarsus of male (presumed sexual dimorphism). Leg tarsi III and IV with a long tactile seta near base. Subterminal setae simple. Leg claws simple. Arolia broad and slightly shorter than claws.

REMARKS

Although Heurtaultia n. gen. clearly belongs in the Cheliferoidea , its exact position is uncertain because of lack of information about some important characters, notably those of the male genitalia, in the fossils. The absence of accessory teeth and the large venedens (implying presence of venom duct) of the fixed finger of the chela would seem to exclude Heurtaultia n. gen. from the crowngroup (sensu Hennig 1969, 1981; Jefferies 1979) of Chernetidae as usually defined. However, some modern Chernetidae lack accessory teeth ( Beier 1948; Hoff 1949; Judson 1985) and a vestigial venom duct is present in the fixed finger of some taxa ( Chamberlin 1931; Beier 1948). An additional character that might exclude Heurtaultia n. gen. from Chernetidae is the presence of eye lenses. With (1906, 1908) emphasized the distinction between “true” eyes (i.e. those with a lens) and eyes that were reduced to spots or absent, when diagnosing his species-groups of Chelifer (s.l.), which have since been recognized as families within Cheliferoidea ( Chamberlin 1931; Weygoldt 1970). Later authors have paid relatively little attention to this character, but Schawaller (1991) noted its usefulness for assigning fossil cheliferoids to families. The only chernetid genus known to have lenses is Gigantochernes Beier, 1932 , but in this case they have an unusual form ( With 1908; pers. obs. of G. rudis (Balzan, 1887)) which might have arisen secondarily.

The well-developed venedens of the movable finger excludes Heurtaultia n. gen. from the crown-group of Atemnidae Chamberlin, 1931 and the slightly oblique nature of the articulation between the femur and patella on the anterior legs, and the basal position of the tactile seta on leg IV exclude it from the crown-group of Withiidae Chamberlin, 1931 .

This leaves the Cheliferidae as the only extant family to which Heurtaultia n. gen. might be assigned. Partial support for such a placement is provided by the elongation of the seta on the tarsus of leg I, which is here interpreted as a secondary sexual character of the genus. Modifications of the tarsus and claws of leg I are found in males of most Cheliferidae , in which they play a role during mating ( Kew 1912; Weygoldt 1966, 1969). These can also entail modifications in the setation of the tarsus, although comparisons with the tarsi of the other legs and with the tarsus of leg I of the female are rarely made in the literature. Sexual dimorphism of leg I, including modified setation in the male, is present in a small number of genera of the Chernetidae ( Muchmore 1997a, b), but in these cases the tibia is always involved (the setation of the tarsus may also be modified in these chernetids, but never on its own).

The proximal position of the tactile seta of the tarsi of legs III and IV distinguishes Heurtaultia n. gen. from all modern genera of Cheliferidae , in which (when present) it is situated near the middle of the segment or in a distal position. This is probably a plesiomorphic character, based on comparisons with non-cheliferoid pseudoscorpions.