Amplaria Chamberlin

Shear, William A. & Krejca, Jean K., 2007, Revalidation of the milliped genus Amplaria Chamberlin 1941 (Diplopoda, Chordeumatida, Striariidae), and description of two new species from caves in Sequoia and Kings Canyon National Parks, California, Zootaxa 1532, pp. 23-39 : 25-27

Amplaria Chamberlin

Diagnosis: Distinct from Striaria in the simpler gonopods. In Striaria , the anterior angiocoxites of the gonopods are sharply angled posteriorly about two-thirds of their length from the base, with distinct transverse rugae at the angle, and terminate in multiple acute spines; the angle and rugae are absent from Amplaria , and the terminations of the anterior angiocoxites are simple, usually lobe-like. The posterior angiocoxites of Amplaria species are clearly bifid, with an anterior branch serving to sheath the flagellocoxites; no such anterior sheathing branch is found in Striaria species. Although a complete survey has not been taken, Amplaria species appear to have a special type of seta on the legs that is not found in Striaria . These setae ( Fig. 14 ) are flattened, curved, and appressed to the leg surface; dorsally they flare into a leaflike shape, and ventrally are divided into many cylindrical filaments. Leg setae in Striaria species are much simpler, appearing as straight, blunt-tipped rods with parallel-grooved shafts. The functional significance of neither setal type is understood.

Description: Striariids of moderate to large size (12–25 mm long). Males: head robust, antennae short, distinctly angled; 2–7 poorly developed and pigmented ocelli irregularly arranged on each side of head; mentum with distinct sigmoid spine at each distal angle ( Fig. 12 ). Mandibles with ventral carina on basal article ( Fig. 12 ). Collum broad, hoodlike; poorly developed transverse groove separates uncrested, rebordered anterior third from posterior two-thirds, anterior median part slightly projecting, roughened with small acute tubercles, posterior section with 12 longitudinal crests, the lateralmost partly suppressed. Trunk segments with 12 longitudinal crests on metazonites, segmental setae located between, not on, crests, usually aciculate. Fourth prozonite with long medial extension on each side, passing between the bases of legpairs three and four. Seventh segment distinctly enlarged. Epiproct three-lobed.

First legs with combs of long, stout, modified setae ( Figs. 5, 6 ) on tibiae and tarsi. Second legs with seminal openings from posterior surfaces of coxae, with or without extended membranous rims, trochanters with heavily setose ventral processes ( Fig. 4 ). Third legs with swollen coxae drawn out into flask-shaped structures, telopodites articulating basolaterally; prefemora slender ( Fig. 13 ). Legpairs 4–7 enlarged, more robust than postgonopodal legs, prefemora and femora dorsoventrally flattened. Gonopods ( Figs. 1–3 , 7–11 , 17–22 ): sternum distinct, well-sclerotized. Gonopod coxae separate and articulated laterally with sternum, with two pairs of angiocoxites, the anterior pair appressed in the midline, straight, with simple lobed terminations, bearing basally three flagellocoxites; the posterior angiocoxite pair larger, sigmoid, with bulky posterior branch, thinner anterior branch sheathing flagellocoxites. Colpocoxites poorly sclerotized, with large lobe extending anterolateral to angiocoxites, smaller posterior lobe often with short, scale-like fimbriae. Ninth legs ( Figs. 15, 16 ) much reduced; sternum deeply bowl-like, receiving at rest the gonopods; coxae short, cylindrical, with gland pore near base, with or without mesal terminal apophysis; telopodites condensed to single article, flattened, heavily sclerotized, setose-tuberculate. Coxae of tenth legs enlarged, bearing coxal gland openings. Coxae eleven unmodified.

Female: similar to male but usually smaller, lacking secondary sexual modifications of the legs; collum shorter, with rounded posterior angles. Segments two and three with distinct ventral marginal carinae. Segment seven not enlarged.

Included species: Amplaria eutypa Chamberlin, 1941 , A. eldora (Chamberlin) 1953 , A. nazinta ( Chamberlin) 1910 , A. shastae ( Causey) 1958 , A. muiri n. sp., and A. adamsi n. sp. (both are described below).

At this time, a key to species would be impractical due to the confusion surrounding eutypa and eldora , and the absence in collections of males of nazinta (and Striaria californica , see below).

Distribution: From the southern Sierra Nevada and San Francisco Bay areas of California north to Shasta Co., California, coastal southwestern Oregon and the southern end of Puget Sound, Washington; at least one species in north-central Idaho, possibly in far western Montana. The San Francisco Bay area records and elements of the distribution north of Shasta Co., California, and in Idaho are based on undescribed species.

Remarks: Striaria causeyae Chamberlin 1940 , from North Carolina, was placed in Amplaria by Chamberlin and Hoffman (1958); examination of the holotype male in the United States National Museum of Natural History (USNM) shows it to be a typical Striaria species.

Amplaria eutypa is unfortunately based on a female. The vial containing the syntypes (USNM) holds parts of two or perhaps three animals, the anterior end of one, posterior end of another, and a second posterior end that may or may not belong to the anterior end. The identity of this species, from nine miles north of Placerville, El Dorado Co., California, cannot be ascertained with certainty until males are collected at or near the type locality. Amplaria eldora , discussed below, is also from near Placerville, collected in Crystal Cosumnes Cave. It is possible these two species are synonyms; eutypa is the senior name. The synonymy cannot be established until the collection of males of both species from their respective type localities. However, a male from Grapevine Cave (in nearby Calaveras County) was seen by Chamberlin (1953b) and determined by him as A. eldora . Its gonopods conform to our concept of Amplaria . Admittedly this is a tenuous chain of logic: eldora may be a synonym of eutypa , and a male purported to be eldora (but not from the type locality) has gonopods that are like those of the two new species described below, therefore we apply the name Amplaria , type species A. eutypa , to the whole group. However, in all the material from the Sierra Nevada and the foothills region to the west WAS has seen so far, only one genus is represented, so we think it unlikely that eutypa does not belong to it.

Amplaria shastae is a very large species, the largest known striariid, found in caves in Shasta Co., California. Males and females have been well-described and illustrated by Causey (1958, 1960) and by Shear (1969). Examination of topotypical specimens makes it clear that despite the inordinate size (25 mm), the gonopods are those of an Amplaria species. Long legs and antennae, depigmentation, and reduced ocelli, together with gigantism, strongly mark A. shastae as a troglobiont. The case is less clear in the two new species described below, which may be at best troglophilic.

Amplaria nazinta , described as a Striaria by Chamberlin in 1910 from Portland, Oregon, and placed in Amplaria by Chamberlin (1941), may or may not belong in the genus; the holotype, a female, has evidently been lost. WAS has seen specimens of several species of striariid from the Portland area but at this point none of them seem to fit the description of nazinta .

Cook’s (1899) Striaria californica (type locality, Sausalito, Marin County, California) is another candidate for membership in Amplaria , but there are other striariid genera, as yet unnamed, in the San Francisco Bay area, and in the absence of males a definite generic assignment is not yet possible. The female holotype (USNM) is in bad condition, having been pinned and dried before being transferred to alcohol. If, as we suspect, Striaria nana Loomis 1936 and Striaria carmela Chamberlin 1947 are both junior synonyms of S. californica (they are certainly synonyms of each other, based on an examination of the types [USNM]; nana is the senior name), it indeed belongs to an undiagnosed genus. Males of nana lack the curved labral spines, the seminal ducts open flush on the surfaces of the second coxae, and the leg setae, while basically leaflike as in Amplaria , do not have the bunches of filaments and are instead drawn out distally into a long, thin extension. The gonopods of this genus do not have the anterior sheathing branch on the posterior angiocoxite division, and in that detail resemble Striaria species.

Figures

FIGURES 9 – 14. Amplaria muiri, n. sp., male, scanning electron micrographs. 9. Gonopods, ventrolateral view; posterior to the right. 10. Gonopods, posterior view. 11. Gonopods, ventroposterior view. 12. Spine at corner of mentum and modified mandibular stipes, anterior view, ventral to the left. 13. Coxae of legpairs 3 – 5, anterior at the top. 14. Modified setae from coxa of leg 3.

FIGURES 4 – 6. Amplaria muiri, n. sp., male, scanning electron micrographs. 4. Coxae and trochanters of second legs of male, ventral view; p, seminal pore; cx, coxa; tr, trochanter. 5. Tibia and tarsus of first leg of male, showing modified setae on ventral surface, posterior view. 6. Modified setae from ventral surface of tibia.

FIGURES 1 – 3. Amplaria eldora, Grapevine Cave specimen, male. 1. Right gonopod, lateral view; aac, anterior angiocoxite; pac, posterior angiocoxite; llcc, lateral lobe of colpocoxite; f, flagellocoxite. 2. Posterior angiocoxite of right gonopod, mesal view. 3. Tip of sheathing branch of posterior angiocoxite, mesal view.

FIGURES 7, 8. Amplaria muiri, n. sp., male. 7. Right gonopod, lateral view. 8. Right gonopod, mesal view.

FIGURES 15 – 18. New species of Amplaria, males, scanning electron micrographs. 15. A. muiri, ninth legpair, anterior view. 16 – 18. A. adamsi, n. sp. 16. Ninth legpair, anterior view. 17. Left gonopod, mesal view. 18. Right gonopod, lateral view.

FIGURES 19 – 22. Amplaria adamsi, n. sp. 19. Right gonopod, lateral view. 20. Right gonopod, mesal view. 21. Tip of internal branch of anterior angiocoxite, lateral view. 22. Same, anterior view.