Causeyella

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 : 26-27

Genus Causeyella , new

Scoterpes, Loomis 1939:181 (not Scoterpes Cope 1872 )

Type species: Scoterpes dendropus Loomis 1939

Included species: Besides the type, Causeyella causeyae , n. sp., and C. youngsteadtorum , n. sp.

Diagnosis: Blind, unpigmented, and with thirty segments, as in Scoterpes , but differing from that genus in the gonopods, in which the ectal coxites are placed directly posterior to the mesal, and in having the front faces of the coxae with trichomes. The gonopods are similar to those of Trigenotyla species, but in Causeyella the coxae of the ninth legs are not strongly extended beyond the joint with the telopodite, and the anterior gonopod coxal faces lack ensiform setae. Prominent trichomes are present on the gonopod coxae of Causeyella species; these are absent in Trigenotyla . Species of Causeyella also average nearly twice the body length of species of Scoterpes or Trigenotyla .

Etymology: For the late Nell Bevel Causey, in recognition of her extensive work on trichopetalids.

Distribution: Caves in southwestern Missouri and northern Arkansas.

Notes: No new descriptive information on any Causeyella species has appeared since 1939. Causeyella species are all evident troglobites of long standing, eyeless and unpigmented and with long legs and antennae. They are the largest trichopetalids, running up to 12–13 mm long, about twice the length of typical Scoterpes species, and nearly three times as long as Nannopetalum vespertilio , the smallest known trichopetalid. After studying a full range of species of Scoterpes , one is struck by how divergent dendropus is from the other species originally placed in that genus. The two new Arkansas forms confirm the distinctiveness of this group of closely related species and at the same time point to a definite relationship with Trigenotyla , also from Arkansas (and Oklahoma). My remarks in 1972 (taken at face value by Peck and Peck, 1982) that Scoterpes and Trigenotyla might someday have to be combined was based on consideration of S. dendropus as a typical Scoterpes , which it turns out not to be.

Scoterpes dendropus was described by Loomis in 1939 from Marvel Cave, Stone Co., Missouri, and has been subsequently recorded from other caves in Stone, Barry and Taney Counties. The first mention of the genus for Arkansas was by McDaniel and Smith (1976), who quote Causey (in litt.) to the effect of the presence of two new species in the state. Youngsteadt and Youngsteadt (1978) combine these two species in their records as “ Scoterpes sp. MS.” Records of Scoterpes from southeastern Missouri (Jefferson and Franklin Counties, “unspecified sites” in Peck and Lewis, 1978) seem to be in error or may be based on misidentifications of Austrotyla specus (Loomis) . In my 1972 monograph, I made reference to, and mapped, a record of dendropus for Illinois Caverns, Monroe County, Illinois. Peck and Lewis (1978) call this “an old M. W. Sanderson record” but make no further reference. Sanderson’s collections are for the most part in NHSI, but no Illinois Scoterpes can be found there. In a recent survey of cave life in southwestern Illinois, Lewis et al. (2003) were not able to verify any Illinois records of Causeyella . Given the extensive work done on the cave faunas of Missouri and Illinois, I think it unlikely that Causeyella from Illinois or from southeastern Missouri would have been overlooked, and these records should be deleted.

As it now stands, the three species of Causeyella occupy three fairly disjunct areas, but all in the White River drainage. The species status of these populations is based on my ability to consistantly separate them, but it is possible that more detailed collecting work in northern Arkansas may reveal intermediates. More biogeographical notes are provided in the species accounts, but to summarize, Causeyella dendropus , except for one Arkansas record ( Fig. 33 ) is found north of the White River, youngsteadtorum (again but for a single record) confined to the region between the White and Buffalo Rivers, and causeyae , the easternmost species, is found on both sides of the White River.

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.