Trichopetalum dux (Chamberlin)

Shear, William A., 2010, 2385, Zootaxa 2385, pp. 1-62 : 19-21

Trichopetalum dux (Chamberlin)

Figs. 14–18, Map 2

Tynopus dux Chamberlin, 1940:57 .

Trichopetalum dux, Shear, 1972:288 , figs. 511–513.

Trichopetalum subterraneum Causey, 1967:129 , figs. 2–5. NEW SYNONYMY.

Types: Male holotype from Duke Forest, Durham Co., North Carolina, in USNM (examined in 1971). Male holotype and male and female paratypes of T. subterraneum from Slacks (=Bryants) Cave , Scott Co. , Kentucky, in USNM and FSCA, examined .

Note on synonymy: The types of Trichopetalum subterraneum are nearly identical in all respects to Virginia and North Carolina specimens of T. dux . Chamberlin (1940) did not illustrate T. dux and described it in a different genus ( Tynopus ), which he compared to Conotyla rather than Trichopetalum . Perhaps for this reason, Causey (1967) did not mention dux in describing subterraneum , and while reviewing the known species of Trichopetalum . The only available checklist in 1967 was Chamberlin and Hoffman (1958), which listed Tynopus dux as a conotylid. The types were in the personal collection of R. V. Chamberlin, unavailable in 1967, and were from a locality far from central Kentucky. Thus, Causey’s description of subterraneum as a distinct species was quite understandable. Ironically, the type specimen of dux was collected by Causey herself (and sent to Chamberlin for identification) in 1939, at the outset of her scientific career. Thirty-eight years later, she unknowingly redescribed the same species under a new name, but from a far-distant locality.

Diagnosis: Distinct in the colpocoxite of the gonopod, which instead of being dentate as in the preceding two species, is in the form of a broad, transverse lamella; the angiocoxite is significantly shorter and straighter than in other Trichopetalum species.

Etymology: There is a Latin word dux , meaning “conductor,” or “guide,” but I suspect that Chamberlin wanted the name pronounced “dukes” to commemorate the type locality in the Duke Forest. In either case, a noun in apposition.

Male from near Blacksburg, Virginia: Length, 5.5 mm, width, 0.75 mm. Color white to pale yellowish tan. Ocelli 8, dorsal row of 6, ventral row of 2; ocelli poorly pigmented. Pregonopodal legs: pairs 3–5 somewhat enlarged compared to postgonopodal legs, pairs 6–7 of normal size. Legpairs 10, 11 with coxal glands; legpair 10 with prefemora and femora smaller, thinner than those of legpair 11. Gonopods ( Fig. 14) with the usual anteriorly swollen sternum and fused coxae, 3 coxal setae on each side in vertical row, coxal trichomes long, prominent. Angiocoxites short, slightly curved posteriorly, tip vaguely emarginate to squared-off; small, lateral, quadrate branch occurs close to base of coxite (ectal coxite of Causey 1967). Fimbriate branch welldefined, somewhat lamellate. Colpocoxite robust, subglobular basally, distally with pointed, transverse lamina. Ninth legpair ( Fig. 15) as usual for genus. Coxae 10 and 11 with glands.

Female from near Blacksburg, Virginia: Length, 6.2 mm, width, 0.80 mm. Nonsexual characters as in male, but ocelli 10, well-pigmented, anterior segments with faint brownish reticulations laterally.

Distribution: For selected records, see Map 2. Material examined (unless noted otherwise, all specimens VMNH): ALABAMA: Lowndes Co.: Wooded hillside 4 mi E of Braggs, 23 April 1960, L. Hubricht, male, females. GEORGIA: Dade Co. : Sutton’s Gulf, 6 April 1999, W. Reeves, male. NORTH CAROLINA: Wake Co.: 4.3 mi S of Cary, hemlock bluffs, no date, no collector, male, females (NCSM). VIRGINIA: Bland Co.: west side of Big Walker Mtn., 6 km E Sharon Springs, 3600’ asl, 9 May 1981, R. L. Hoffman, male, female. Grayson Co.: Comer’s Rock, Iron Mountains, 4000’ asl, 12 December 1965, R. L. Hoffman, male, female; Whitetop Mtn., south slope on SR600, 5000’ asl, 23 December 1984, R. L. Hoffman, males, females. Henry Co.: along creek near Leatherwood, 2 May 1959, R. L. Hoffman, females. Montgomery Co.: Price’s Fork Hollow, 5 mi W of Blacksburg, 1900’ asl, 20 April 1976, W. A. Shear, male, female; Toms Creek, 3 mi N of Blacksburg, 27 February 1951, R. L. Hoffman, males, females. Patrick Co.: Kibler Park, below Pinnacles Powerhouse, 8 April 1961, L. Hubricht, male, female. Smyth Co.: North side of Whitetop Mtn. on SR600, 3500’ asl, 4 May 1964, R. L. Hoffman, male, female. Washington Co.: junction of SR614 and 612, 3 mi NE of Mendota, 3 December 1997, R. L. Hoffman, males, females. WEST VIRGINIA: Cabell Co.: Kilgore Creek, 2mi N, 2.7 mi E of Milton, 650’ asl, N38.45°, W82.1°, 20 February 1998, W. Arnold, male, female (WAS).

Literature records: Shelley (1978) reports T. dux from Chatham Co., and Filka and Shelley (1980) have it from Gaston Co., NORTH CAROLINA, but both these records are based on females or juveniles.

Trichopetalum dux may be expected to occur in the piedmont regions of GEORGIA and SOUTH CARO- LINA, based on existing Alabama, Georgia and North Carolina records. Further collecting should reveal the species general through WEST VIRGINIA (the Bland Co., Virginia, record is very close to the West Virginia border) and at least eastern and central KENTUCKY. Sympatry with T. uncum could occur in central Kentucky or piedmont South Carolina, with T. lunatum in northern West Virginia, with T. jerryblatti in southern West Virginia, and with T.dickbrucei near the Blue Ridge front in North Carolina . The concentration of localities of T. dux in Virginia is a result of collecting bias: R. L. Hoffman has thoroughly collected in the state at all seasons, including winter and early spring. Similar efforts should fill in the implied gaps in the species’ distribution between the outliers in West Virginia, Kentucky (“ subterraneum ”) and Alabama.

Notes: Given the fact that Hoffman has collected in Virginia most intensively in the spring and summer, the winter records of mature specimens of dux make a good case for cold-weather maturity and activity of the species. Many of the Virginia localities are from high elevations to 5000’ (1524 m), but the species is also found in the piedmont at elevations less than 1000’ (305 m). Ecological notes on labels are very few; two collections were made using Berlese funnels, and one was from a pile of sawdust .

I have illustrated ( Figs.16, 17) spermatophores on both the gonopods of males and the cyphopods of females ( Fig. 18) from the Washington Co., Virginia, population, taken in December. A single female from Montgomery Co., collected in February, was also carrying a spermatophore. These are the first spermatophores recorded from either anatomical site for any North American chordeumatidan milliped, though putative spermatophores have been found previously, associated with the coxal glands of the tenth legpair. The spermatophores are orange in color and contrast strongly with the white animals; at first I thought them to be the bizarre, heavily sclerotized gonopods of a unique new species. However, closer examination showed their true nature. The spermatophores are much too large to have been formed in the coxal glands of the tenth legs, which are too small to hold them by at least an order of magnitude. The shape and appearance of these spermatophores casts doubt on the nature of previously reported spermatophores emerging from the tenth legpair coxal glands, which tend to show up as small, coiled, coagulated and rather unformed masses. How the dux spermatophores are formed and how they function can only be a subject for speculation. While only three males were available carrying the spermatophores, the form was constant from specimen to specimen and on the single female. It is possible that one function of the gonopods is to mold or shape this spermatophore, which is then transferred to the female. In both scorpions and pseudoscorpions, which mate by spermatophore transfer, an internal mold in the male genitalia forms the species-specific shape of the spermatophore. A function for the fimbriate branch of the gonopod could be to hold the spermatophore firmly attached to the gonopods until it is transferred, perhaps softened by a secretion. The real answer will not be known until mating can be studied under controlled conditions, not a likely event given the obvious practical difficulties.