Sequoiadesmus krejcae, Shear, William A. & Shelley, Rowland M., 2008

Shear, William A. & Shelley, Rowland M., 2008, Cave millipeds of the United States. VI. Sequoiadesmus krejcae, n. gen., n. sp., from Sequoia and Kings Canyon National Parks, California, USA (Diplopoda, Polydesmida, Polydesmidea, Macrosternodesmidae)., Zootaxa 1693, pp. 41-48 : 43-47

Sequoiadesmus krejcae , n. sp.

Figs. 1–8

Type specimens. Male holotype and one male and one female paratype ( CAS) collected by J. Krejca, A. Gluesenkamp, C. Walk, J. Despain, & N. Barth, 9 July 2004, in Hurricane Crawl Cave, SNP, Tulare Co., California.

Diagnosis. With the characters of the genus.

Holotype. Length, 5.4 mm, maximum width 0.6 mm. Head (figs. 1, 2) smooth but with moderately dense pilosity. Antennae short, clavate, and densely pilose, reaching back to caudal margin of 2nd tergite, relative lengths of antennomeres 6>2=3=4>5>7>1, articles 2–4 twice as long as wide and slightly clavate, 5 slightly wider than long, 6 subovoid and swollen. No accessory sensory areas detected. Collum (figs. 1, 2) small and subovoid, overlapping epicranium, with acute posteriolateral angles and indistinct lateral teeth; surface smooth, with anterior-anteriolateral row of 15 long, acute setae, posterior row of 11 similar setae, and ca. 15 additional, scattered, dorsal setae. Metaterga of succeeding segments (fig. 3) smooth, virtually without paranota, with 3 acuminate lateral setae anterior to ozopores subtending small marginal teeth, about 15 setae on caudal margins posterior to ozopores, 10–13 setae in anterior rows, and ca. 15–22 scattered dorsal setae. Caudal segments with dorsal setae arranged in 3 transverse rows. Limbi smooth. Ozopores (fig. 3) with slightly raised rims. Epiproct setose and subtriangular, sides tapering evenly to tip; spinnerets not set in depression.

Sterna unmodified. Legs moderately long; prefemora of pregonopodal legs not swollen. Gonopodal aperture (fig. 6) broadly ovoid, occupying entire breadth of metazonite but not extending onto prozonite. Gonopods (figs. 4–8) with coxae globular, completely filling respective halves of aperture, narrowly segregated anteriorly, contiguous, deeply excavated anteriorly; prefemora moderately transverse, setose. Process B with two unequal distal branches, lateral one short and blunt, mesial branch longer and expanding apically into shallowly indented, "T-shaped" termination. Acropodite with long, distally curved solenomere giving rise to short, apically blunt distal zone at 1/3 of length. 9th legs unmodified.

Female paratype. Length, 5.7 mm, width 0.6 mm. Nonsexual characters as in male.

FIGSURES 1–3. Scanning electron micrographs of S. krejcae holotype. 1, head and segments 1–6, dorsal view. 2, head and collum, dorsal view. 3, segment 5, dorsal view.

FIGSURES 4–6. Scanning electron micrographs of gonopods in situ of S. krejcae holotype. 4, posterior view. 5, lateral view. 6, anterioventral view.

Distribution. The following female specimens are consistent with the female paratype but cannot be authoritatively assigned to S. krejcae given the difficulties in distinguishing species in female and juvenile polydesmideans.

FIGSURES 7–8. Line drawings of dissected S. krejcae left gonopods. 7, lateral view. 8, mesial view.

CALIFORNIA: Tulare Co., SNP, Clough Cave, f, 27 April 2004, J. Krejca, P. Sprouse, B. Fryer, D. Ubick, P. Paquin (CAS); KCNP, Grant Grove Section, Lilburn Cave, ff, 30 July 2003, J. Krejca, V. Loftin, S. Fryer, J. Snow, A. Snow, B. Oost (CAS).

The caves in SNP and KCNP comprise five clusters (fig. 9); Hurricane Crawl Cave, the type locality, is in cluster 2. Lilburn Cave is in cluster 1, about 5 miles (8 km) north-northwest of cluster 2, and Clough Cave in is cluster 5, about 14 miles (22.5 km) south of cluster 1. Adult males are needed to determine whether forms in these caves are conspecific with krejcae . The presence of more than one species is a definite possibility, since clusters 2 & 5 harbor distinct species of the troglophilic milliped genus Amplaria Chamberlin, 1941 ( Chordeumatida : Striariidae ) ( Shear & Krejca 2007).

Etymology. The species name honors Jean K. Krejca, who organized and led the several expeditions to the caves of Sequoia National Park, and participated in collecting this and other species.

Remarks. At this point it is not possible to assess the ecological status of S. krejcae . Is it a troglobite, a troglophile, or an edaphobite to be found only occasionally in caves? Both troglobitic and edaphobitic minute polydesmidans tend to be depigmented, and of course, all polydesmidans are eyeless. Figs. 1–3 show that the legs and antennae of the species are not elongated nor attenuate, and the cuticle is well-calcified. Since very little collecting has been done outside caves in the region, we are not at all confident that S. krejcae is caveliimited.

Our assignment of S. krejcae to the Macrosternodesmidae is somewhat tentative since not all the diagnostic familial characters are evident and others are equivocal. The distal zone could be interpreted as homologus to the process close to the pore of the prostatic groove in the Polydesmidae , and what we label as process B, which is characteristic of macrosternodesmids, could also be a polydesmid “tibiotarsus”; finally, the pregonopodal legs lack the dorsally inflated prefemora that occur in other macrosternodesmids. Some gonopodal features of Sequoiadesmus are similar to those of the Californian “polydesmid” genus Bidentogon Buckett and Gardner, 1968 , which is atypical within Polydesmidae , and may require a new family. We therefore hypothesize the present assignment pending further research toward our aforementioned goals with the Polydesmoidea and Trichopolydesmoidea.

FIGSURE 9. Map of parts of Sequoia and Kings Canyon National Parks, Tulare Co., California, showing locations of caves studied in 2003–2004 by Jean K. Krejca and associates. Note that some of the cave names are shortened for ease of viewing on the map, typically the word Cave is left off. See text for the full names of caves in which Sequoiadesmus krejcae specimens were collected.