Causeyella youngsteadtorum, Shear, William A., 2003

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 : 31-33

Causeyella youngsteadtorum , n. sp.

Figs. 25–32

Types: All specimens, FSCA. Male holotype, female paratype from ARKANSAS, Boone Co., Brewer Cave (T16N, R18W, S8), collected July/ August 1976 by Norman and Jean Youngsteadt. The following specimens are paratypes: ARKANSAS: Boone Co., Major’s Cave (T16N, R20 W, S16), July 1977, N. and J. Youngsteadt, 3 females. Newton Co.: Lewis Spring Cave (T16N, R19W, S12), January 1976, N. and J. Youngsteadt, male, female; “Cave” (T17, R19W), June/ July 1976, N. and J. Youngsteadt, male, female. Searcy Co.: Hurricane River Cave (T16N, R13W, S7), N. and J. Youngsteadt, January/ February 1976, male; Woods Hollow Cave #1, 16 March 2002, G. Greening, C. Brickey (SBP); Thruway Cave, 31 July 2002, M. Slay, male, female (SBP).

Diagnosis: Very similar to C. causeyae , but the ectal angiocoxites are more spatulate, and the mesals are shorter and have two subequal apical teeth.

Etymology: named for Norman and Jean Youngsteadt, in recognition of their collection of nearly all known specimens of this species and their contributions to Arkansas biospeleology.

Male holotype: Nonsexual characters as described for C. causeyae . Gonopods (figs. 25, 27–29) with well developed sternal lobes. Anterior surfaces of coxae entirely covered with prominent scaly trichomes not becoming notably larger distally; about 15 setae on each coxa, not separated into groups; mesal coxites (aac, Figs. 27, 29 ) in anterior view strongly spatulate, ectal coxites (pac, Fig. 29 ) less than half their length, broad in lateral view, with subequal apical teeth. Lamellate branch of colpocoxite (fb, Figs. 27, 29 ) very large, curled at tip, posteriorly divided into 3–4 smaller branches, roughened with rows of blunt trichomes, extending anterior of mesal coxites. Ninth legpair ( Figs. 26 , 31 ) with coxae laterally flattened, mesally excavated, bearing vestigial glands, articulation of prefemora offset laterally; prefemora longer than coxae, two or three vaguely indicated articles distally, claw short, twisted. Legpairs 10, 11 with glands, unmodified.

Female paratype: Length, 13.5 mm, width 1.05 mm. Nonsexual characters as in male. Intact female depicted in Fig. 30 .

Distribution: As given under Types, above. Literature records: Youngsteadt and Youngsteadt (1978) record the species from Potato Cave, Searcy Co., very close to Hurricane River Cave, but these specimens were not found with the others from their survey in the Causey collection. Fitton Cave and Peccary Cave in Newton Co. were not visited by the Youngsteadts in their survey of northern Arkansas caves ( Youngsteadt and Youngsteadt, 1978), but as detailed above under C. dendropus , at least the former cave supports that species. Except for one record ( Fig. 33 ), youngsteadtorum occurs in the region south of the White River, but north of the Buffalo River. The Buffalo River flows in a deep gorge and may be enough of a barrier to separate youngsteadtorum from causeyae .

Figures

FIGURE 33: Inset map shows the eastern and midwestern United States; filled circles are records of species of Nannopetalum, box shows area of larger map (parts of Oklahoma, Arkansas and Missouri). On larger map, dashed lines are state borders, dotted lines county borders; open squares, Causeyella dendropus; filled squares, C. causeyae; half­filled squares, C. youngsteadtorum; filled circles, Trigenotyla parca; open circles, T. vaga; circles with lower half filled, T. blacki; circles with upper half filled, T. seminole.

FIGURES 22 – 26. Causeyella dendropus Loomis, 22, gonopods, anterior view. C. causeyae, n. sp., 23, 24. 23, gonopods, anterior view. 24, male ninth legs, anterior view. C. youngsteadtorum, n. sp., 25, 26. 25, gonopods, anterior view. 26, male ninth legs, anterior view. Scale lines = 0.1 mm (100 µm) for Figs. 22, 23, 25, 0.5 mm (500 µm) for Figs. 24, 26.

FIGURES 27 – 29. SEMs of Causeyella youngsteadtorum. 27, gonopods, ventral view. 28, gonopod fimbriate branch. 29, gonopod tips, oblique lateral view. Scale lines as labelled.

FIGURES 30 – 32. SEMs of Causeyella youngsteadtorum. 30, female, lateral view. 31, ninth legs of male, anterior view. 32, outermost segmental seta of left side of segment 12, showing typical secretion. Scale lines as labelled.