Octoglena Wood, 1864

Shelley, Rowland M., Richart, Casey H. & Bogan, Arthur E., 2010, Octoglena claraqua, n. sp. (Polyzoniida: Hirudisomatidae), a new milliped from Idaho, USA; first record of the order from the western interior of North America, Zootaxa 2446, pp. 55-64 : 56-57

Genus Octoglena Wood, 1864

Octoglena Wood, 1864:186 ; 1865:229. Bollman, 1893:117, 137, 187. Jeekel, 1971:41. Hoffman, 1980:73; 1999:29. Shelley, 1996:108 –112; 2002b:92.

Hypozonium Cook, 1904:62 . Cook and Loomis, 1928:17. Chamberlin and Hoffman, 1958:187. Buckett, 1964:29. Jeekel, 1971:39. Hoffman, 1980:73. Kevan, 1983:2962.

Euzonium Chamberlin, 1950:1 . Chamberlin and Hoffman, 1958:187. Buckett, 1964:29. Jeekel, 1971:38. Hoffman, 1980:73.

Type species. Of Octoglena , O. bivirgata Wood, 1864 , by monotypy; of Hypozonium , H. anurum Cook, 1904 , by monotypy; of Euzonium , E. crucis Chamberlin, 1950 , by original designation.

Description (adapted from the diagnosis in Shelley (1996)). Dorsum variably colored, either subuniformly pale yellow to white, with three dark longitudinal stripes on both pro- and metazona, or with transverse bands on prozona ( Fig. 1 ). Dorsum convex and glabrous, smooth or lightly granular. Prozona relatively long, elevated above and extending entire widths of metaterga, strictures distinct, ridged; paranota absent; caudal metatergal margins detached from succeeding tergites, elevated and upturned to varying degrees; body broad (W/L ratio varying from 27–38%), flattened "bell-shaped" in profile, sides extending strongly laterad. Head strongly pyriform ( Fig. 4 ) with fine, light setation; three ocelli on each side arranged linearly in pigmented, diverging rows arising at level of antennal sockets and extending onto epicranium; antennae and antennomeres relatively short, becoming progressively more hirsute distad. Collum broad, overhanging epicranium and at least one pair of ocelli ( Fig. 4 ); telson either broad and comprising nearly entire caudal width, or relatively narrow and comprising around half of breadth. Sterna moderately broad, opposing coxae separated in midline. Legs lightly hirsute, extending to lateral margins of body, podomeres small, claws indistinct.

Gonopods in situ either upright and directed subventrad or recumbent and directed anteriad ( Figs. 2–3 ). Anterior gonopods either curving submediad and overhanging sternal lobes or upright and lying parallel to latter; sterna with strong, rounded, apically hirsute lobes segregated to varying degrees; ultimate podomeres either in form of calyx ( Fig. 6 ) or divided, with broad, hirsute, ventral lobes of varying sizes usually overhanging glabrous, dorsal counterparts, latter either short, broad, and apically blunt, curved slightly ventrad, and directed anteriomediad, or long, narrow, and acuminate, slightly sinuate and directed sublaterad; corners of 4th and 5th podomeres either extended on caudal sides or latter with variably broad, curvilinear or sinuate projection ( Fig. 7 ); coxae with or without hirsute lobes, lengths variable. Posterior gonopods with ultimate podomeres simple and acicular, apically acuminate, fimbriate, angled, or lightly hirsute, projecting anteriad between dorsal and ventral lobes of anterior gonopod ultimate podomeres.

Species. Six.

Distribution. The Pacific Coast of North America from the vicinity of Vancouver (city), BC, to Santa Cruz Co., California, extending inland to the western slope of the Cascade Mountains from BC to central Oregon and the eastern slope of the Coast Range in southern Oregon and California, with localized, allopatric species some 74 and 320 mi (120 and 512 km) to the east in California and the Idaho Panhandle, and a widespread species in the southeastern US extending from westcentral South Carolina to southcentral Tennessee and northwestern Alabama ( Fig. 9 ).

Occurring along the Pacific Coast and in the southeastern states, the distribution of Hirudisomatidae is congruent with that of Andrognathidae (Platydesmida) ( Shelley et al. 2005), which also occurs in northern Idaho ( Gardner 1975, Hoffman 1999). Discovery of Hirudisomatidae in the latter is thus not surprising because congruence in the first two areas is matched in the third.

Figures

FIGURE 9. Distribution of Hirudisomatidae in North America and the Western Hemisphere. Star, Mexiconium and M. absidatum; dot, Octoglena sierra; triangle, Octoglena claraqua; outlined areas, Octoglena spp.

FIGURES 1 – 4. Octoglena claraqua holotype. 1, lateral view of entire specimen showing color pattern. 2, ventrolateral view of entire specimen showing recumbent gonopod complex. 3, the same of anterior end; ag, anterior gonopods, pg, posterior gonopods. 4, anterior view of head, antennae, and collum.

FIGURES 5 – 8. Octoglena claraqua, somatic and gonopodal features. 5, telson and segments 25 – 27, dashed line denotes the area of the paraprocts and anus; scale line = 0.5 mm. 6, left anterior gonopod and sternum, anterior view. 7, right gonopods, caudal view. 8, right posterior gonopod, sublateral view. 25 – 28, segment numbers. Scale line for fig. 5 = 0.5 mm; line for figs. 6 – 8 = 0.05 mm.