Aulodrilus cernosvitovi du Bois Reymond Marcus, 1947

Ohtaka, Akifumi, 2021, Taxonomical study of Japanese Aulodrilus Bretscher (Annelida, Clitellata Tubificinae) with descriptions of two new species, Zootaxa 4952 (1), pp. 1-32 : 21-22

Aulodrilus cernosvitovi du Bois Reymond Marcus, 1947

( Figure 15 )

Aulodrilus cernosvitovi du Bois Reymond Marcus, 1947 : pl. 2, figs 15–19, pl. 3. figs 20–21.

Aulodrilus cernosvitovi du Bois Reymond Marcus : Howmiller 1974: 9, fig. 2.

Aulodrilus pigueti Kowalewski : Brinkhurst 1971: 526, fig 8.23I (in part); Brinkhurst and Marchese 1987: 3157, fig. 1 (in part).

Material examined. USNM 102745–102746, two whole-mounted mature specimens. Saladillo River, Santa Fé Province, Argentina, coll. E. de Drago and R. Regner in 1984. R. O. Brinkhurst identified and registered. They were used under the name of Aulodrilus pigueti in Brinkhurst & Marchese (1987).

Brief description. Dorsal hairs from VI, 2–6 per bundle. Dorsal crotchets in anterior segments 7–15 per bundle, with upper tooth shorter and thinner than lower one. Dorsal bifid crotchets replaced by 5–9 oar-shaped chaetae from IX to X. Distal parts of oar-shaped chaetae oval to rhombic in shape with midribs ( Fig. 15A,B ). Ventral chaetae all bifid crotchets with upper tooth shorter and thinner than lower one, 8–14 per bundle in anterior segments. No lateral wings on chaetae. Male ducts in VII with short vasa deferentia and tubular atria, separately opening into male bursae in front of ventral chaetal bundles in VII ( Fig. 15C ). Ventral chaetae in atrial segment not modified, 6–8 per bundle. Single solid prostates as large and atria. Spermathecae absent in one specimen, USNM-102746, while present in VI in another USNM-102745. In the latter specimen, spermathecae ampullae large and spherical with loose sperms.

Remarks. Aulodrilus cernosvitovi had once been regareded as a junior synonym of A. pigueti by Brinkhurst (1971); subsequently it has been regarded as a distinct species by Brinkhurst & Marchese (1989) and Ohtaka & Usman (1997). The present examination of non-type material of A. cernosvitovi from Argentina confirmed midribs on the oar-shaped chaetae, which is unique within the genus, and was described in the original description ( du Bois Reymond Marcus 1947) and subsequent redescription ( Howmiller 1974). In the present material, the midribs on the oar-shaped chaetae were not developed in anterior segments ( Fig. 15A ), although they become prominent in posterior segments, where the distal ends changed from oval to rhombic in shape ( Fig. 15B ). Tubular atria, separate openings of male pores in VII, and absence of penial chaetae, described in the original description were confirmed in the present examination; all of these are different from A. pigueti . In the figures ( du Bois Reymond Marcus 1947: figs 20A,B, 21) of the original description of A. cernosvitovi , vasa deferentia are shorter than atria and they join with atria subapically. On the other hand, in the present material, vasa deferentia are as long as or longer than atria, and they join with atria almost apically. These characters could vary depending on the fixation and orientation. In addition, absence of spermathecae was described in the original description of A. cernosvitovi ( du Bois Reymond Marcus 1947) , while a pair of large spermathecae containing loose sperm was found in one of the two mature Argentine specimens examined in the present study. The presence or absence of spermathecae should be regareded as intraspecific variation in A. cernosvitovi .

Distribution. Aulodrilus cernosvitovi has been recorded from Central to South America, including northern Brazil ( du Bois Reymond Marcus 1947), Nicaragua ( Howmiller 1974), and northern Argentina ( Brinkhurst & Marchese 1987, under the name of A. pigueti ; Brinkhurst & Marchese 1989; present study). Brinkhurst & Marchese (1989) recorded Aulodrilus pigueti along with Aulodrilus cernosvitovi in South and Central America. It is uncertain whether the record of A. pigueti of Brinkhurst & Marchese (1987) from Peru should be assigned to A.cernosvitovi or not.

Figures

FIGURE 15. Chaetae and genital organs in Aulodrilus cernosvitovi du Bois-Reymond Marcus from Argentina (USNM 102746). A, dorsal oar-shaped chaeta in an anterior segment; B, distal end of oar-shaped chaetae in a posterior segment; C, ventral view of male ducts.