Trigenotyla parca Causey

Shear, William A., 2003, The milliped family Trichopetalidae, Part 1: Introduction and Genera Trigenotyla Causey, Nannopetalum n. gen., and Causeyella n. gen. (Diplopoda: Chordeumatida, Cleidogonoidea), Zootaxa 321, pp. 1-36 : 19-22

Trigenotyla parca Causey

Figs. 9–12

Trigenotyla parca Causey 1951:118 , figs. 1–5; Shear 1972:280. figs. 527, 528.

Types: Male holotype, 5 male and 5 female paratypes from Blue Spring, Carrol Co., Arkansas, collected 29 October 1949 (FSCA). Causey (1951) stated the types would be deposited in the collection of the Academy of Natural Sciences, Philadelphia, but there is no record they ever arrived there. Hoffman (1999) suggests, with a question mark, the Illinois Natural History Survey, where other specimens described in the same paper wound up, but the material is not to be found there, either. The Florida State Collection of Arthropods received Causey’s personal collection after her death. There I found specimens with the appropriate data labelled as paratypes, but unfortunately at some point the vial had been filled with water, not alcohol, and the specimens had rotted to bits. Another vial was labelled by Causey as “Trigentalum glesum Causey, male holotype, female paratype ” and with the same collection data as given above. These specimens are undoubtedly the types of Trigenotyla parca . However, the gonopods of the male are missing, and while Causey’s collection included a box of microscope slides on which trichopetalid genitalia had been permanently mounted, a slide of T. parca was not among them.

Diagnosis: Distinct in the needle­like ectal coxite from T. seminole and T. vaga , where this structure is laminate and toothed; the latter two species also lack ensiform gonopod setae. In T. blacki , the ectal coxite is entirely missing.

Etymology: parca is a Latin adjective meaning (in this sense) “small.” A more common meaning is “frugal, thrifty.”

Male from Blue Spring: Length, 6.7 mm, width 1.0 mm. Color brown, mottled darker especially along dorsal midline. Segmental setae on midbody segments equal to segment width, segmental shoulders prominent, paranota­like. Fifteen to 17 ocelli in four irregular rows forming triangular eyepatch. Pregonopodal legs slightly crassate; femora of sixth legs enlarged, with distal ventral swelling.

Gonopods ( Figs. 9 , 12 ) with prominent sternal swellings; coxae (cx, Fig. 9 ) fused in midline, bearing two groups of prominent strongly ensiform setae ( Fig. 10 ); lateral setal group of 16–22 arranged along lateral margins of coxae, distally raised on strong lobe at lateral distal margin. mesal group of 3 setae near midline. Anterior coxites (aac, Fig. 9 ) curved, acute, posterior edges irregularly serrate; ectal coxites (pac, Fig. 9 ) thin, needlelike; fimbriate branch relatively large ( Fig. 12 ). Ninth legpair ( Fig. 11 ) with L­shaped coxae bearing vestigial glands; telopodite of single article (prefemur) arises near midpoint on ectal side. Legpairs 10, 11 with coxal glands, otherwise unmodified.

Female from Blue Spring: 6.4 mm long, 0.9 mm wide, nonsexual characters as in male.

Distribution: Material examined: ARKANSAS: Madison Co.: Combs, no collector or date, male (FSCA). Newton Co.: Bat Cave, T15N, R23W, sec. 15, 8 June 1977, no collector, female (FSCA); Len House Cave, Buffalo National River, 15 July 1977, no collector, males, females (FSCA). Washington Co.: Granny Dean Cave, 10 mi S Fayetteville, 9 June 1969, S.& J. Peck, male (WAS); Devils Den State Park, 13 July 1949, M. W. Sanderson, L. Stannard, male (INHS).

Causey (1951) states that the species has been collected at “several places” in Washington Co., but I have seen no specimens aside from the records listed above. I predict that T. parca will be found generally throughout Arkansas north of the Canadian River, and probably also in adjoining Oklahoma and Missouri.

Notes: While it is likely that all the records are from caves, in two cases specific caves are not mentioned in the data. But trichopetalids are not likely to be captured outside caves in summer. The pigmentation and well­developed eyes suggest that T. parca is troglophilic, not troglobitic.

Figures

FIGURES 9 – 11. SEMs of Trigenotyla parca Causey. 9, gonopods, anterior view. 10, ensiform setae of gonopod, anterior view. 11, ninth legs of male, anterior view. Scale lines as labelled.

FIGURES 12 – 15. Trigenotyla parca Causey, 12, gonopods, anterior view. Trigenotyla blacki n. sp., 13 – 15. 13, gonopods, anterior view. 14, male ninth legs, anterior view. 15, male right sixth leg, posterior view. Scale lines for Figs. 12 – 14 = 0.1 mm (100 µm), for Fig. 15, 0.5 mm (500 µm).