Ocnerodrilus imperialis James, Bartz & Brown, 2023

James, Samuel W., Bartz, Marie L. C. & Brown, George G., 2023, New Ocnerodrilidae genera, species and records from Brazil (Annelida: Crassiclitellata), Zootaxa 5255 (1), pp. 235-269 : 262-263

Ocnerodrilus imperialis James, Bartz & Brown , sp. nov. ( Fig. 16 a-d)

Holotype. BRRJDNA0059, one adult, Tinguá Biological Reserve , Rio de Janeiro state, Brazil, S22.57007 ˚ W43.46864 ˚, 795 m asl., in wet stream bank sediment; 02 April 2014, G.G. Brown, S.W. James, A.C. Buch, L.F. Lourençato, and M.L.C. Bartz, colls.

Paratype. BRRJ0012 , 1 adult, 6 juveniles, same data as holotype .

Etymology. The species is named for the Estrada Imperial, the old road from the former Brazilian imperial capital in Rio de Janeiro city to the summer location of the imperial court in Teresopolis Petrópolis.

Description. Dimensions 38-56 mm by 1.3-1.4 mm at segment x, 1.2-1.3 mm at clitellum, 1.4-1.5 mm at xxx, body cylindrical, segments 84-97. Setae closely paired throughout, CD below lateral; setal formula AA:AB:BC:CD = 4:1:4:1 at x, 3.3:1:4:1 at xxx, DD> ½ circumference. Prostomium epilobous open; segments lacking secondary annulations, unpigmented, no dorsal pores, spermathecal pores wide slits with tumid lips in 8/9, centered on B. Ovipores transverse slits in xiv in B just behind 13/14; male and prostatic pores with common secondary opening in transverse slit openings within thickened porophores on xvii. Primary male and prostatic pores in xvii on floor of shallow invagination. Setae AB absent in xvii. Clitellum in ½xiii, xiv-xviii, saddle shaped reaching down to A setal line; genital markings absent ( Fig. 16a, b ).

Septa 5/6-9/10 muscular, 11/12/13 less so. Alimentary canal without gizzard; esophageal glands in v-viii, esophagus with long valve in xii-xiii, intestinal origin in xiv, no typhlosole. Calciferous glands oblong, paired in ix, dorso-laterally connected to esophagus, with solid walls surrounding irregular central lumen ( Fig. 16c ); each gland with blood vessel from anterior end to extra-esophageal vessel, and blood vessel from posterior end of gland to supra-esophageal vessel. Holonephric, first nephridia in segment v, tubular throughout within BC-D level of segments.

Vascular system with ventral trunk, single dorsal trunk, lateral vessels in v-ix, latero-esophageal hearts in x-xi.

Ovaries and funnels free in xiii; paired spermathecae in ix, consisting of short narrow muscular duct, sharply demarcated ovate ampulla ( Fig. 16c ).

Male sexual system holandric, testes and funnels enclosed in very delicate membranous sacs in x, xi, vas deferens superficial on body wall from 10/11 to xvii where it enters body wall at anterior edge of prostatic duct; seminal vesicles in xii extending into xiii, seminal vesicles with stalked attachment to posterior face of 11/12. Tubular prostates folded under intestine within xii-xix; prostatic ducts slightly muscular, about one segment long; glandular portions three times the diameter of the ducts ( Fig. 16d ), no copulatory bursae, or other thickened ends of prostatic ducts or vasa deferentia. Transverse muscle bands in xvii-xix.

Remarks. Ocnerodrilus imperialis sp. nov., unlike the most common species O. occidentalis Eisen, 1878 is fully hermaphroditic with male funnel iridescence and large volumes of sperm enclosed in segments x and xi.

Gates (1973) characterized the entire genus as having an intestinal origin in xii, but Righi (1994) does not include that character in his diagnosis of Ocnerodrilus . The present species has a distinct, long esophageal valve in xii and xiii, with the intestinal origin in xiv. Therefore, one can dismiss all species known to Gates as being senior names of O. imperialis sp. nov. That leaves 5 species, all described by Righi and a collaborator, from South American and Costa Rican specimens: O. alox Righi & Merino, 1987 , O. andinus Righi, 1981 , O. ibemi Righi, 1968 , O. ipu Righi, 1975 , and O. potyuara Righi, 1994 . The new species is distinct from O. alox , another apparently amphimictic species, which has an intestinal origin in xii, spermathecal pores in 7/8 and seminal vesicles in ix and xii. Ocnerodrilus andinus is very small (10 mm vs. 41-56), the intestinal origin is in ½xii, and the calciferous gland walls are very simple, without blood sinuses and longitudinal structure. The male field of O. ibemi consists of a roughly hexagonal elevated glandular area around the male/prostatic pores, which is not present in O. imperialis sp. nov.. The two also differ in the intestinal origin. In Righi’s (1994) key, O. ibemi is said to have internal longitudinal folds or trabeculae in the calciferous glands; this character is not described in Righi (1968). Such folding is minimal if present, in O. imperialis sp. nov.. A darkly pigmented species O. ipu has two pairs of spermathecae and seminal vesicles in ix and xii, among other differences from O. imperialis sp. nov.. Compared to O. potyuara , the new species lacks seminal vesicles in ix, the seminal vesicles are stalked, not sessile on septum 11/12; it has a more posterior intestinal origin, the male and prostatic porophores have pronounced slits rather than being rounded papillae, and the prostates are folded under the gut anterior to the prostatic segments. A nomenclatural note: the name is spelled “potyura” in the abstract (p. 89) but “potyuara” elsewhere, including a species list for the genus (p. 93), several points about morphological diversity within Ocnerodrilus (p. 94), a key to the species of Ocnerodrilus (p. 96), the species description itself (p. 96), figure legend (p. 97), and remarks on the species and comparisons to others (p. 98) ( Righi, 1994). The DNA barcode for the holotype is in the Supplemental Information: BRRJDNA0059.

Figures

FIGURE 16. Ocnerodrilus imperialis sp. nov. A. Ventral view with spermathecal pores (sp); B. Ventral view with male pores (mp), scale bar 1 mm; C. Internal view of calciferous gland (cg) in situ and cross section and spermatheca (s); D. Prostate gland p.