Doliodrilus puertoricensis Erséus and Milligan, 1988

Wang, Hongzhu & Erséus, Christer, 2004, New species of Doliodrilus and other Limnodriloidinae (Oligochaeta, Tubificidae) from Hainan and other parts of the north-west Pacific Ocean, Journal of Natural History 38 (3), pp. 269-299 : 292-294

Doliodrilus puertoricensis Erséus and Milligan, 1988

(figure 12)

Doliodrilus puertoricensis Erséus and Milligan, 1988: 12–15 , figure 2; Erséus, 1990b: 277.

New material. SMNH Main Coll. 43713–43714, two whole-mounted specimens from New Caledonia, Touhou, N of E end of point at Kombounou , 20°46.6∞S, 165°14.4∞E, mid-intertidal, pebbles, gravel, sand and black mud; 18 September 1993, coll. C. Erséus (Station NC 93-45) .

Brief description of new material. One complete specimen 7.7 mm long, 51 segments. Diameter at XI about 0.4 mm. Prostomium blunt. Clitellum extending over XI–XII. Chaetae 40–45 m m long, about 2.5 m m thick, with upper teeth variable in length but thinner than lower (figure 12A); (one) two to four per bundle anteriorly, (one) two (three) per bundle in post-clitellar segments. Pharyngeal glands in IV– V. Chloragogen cells from VI onwards. Oesophagus in IX barrel-shaped, thick-walled and granulated; semi-embedded blood plexus permeating dorsal region. In the complete specimen, irregular blood plexus also present in posterior third of oesophagus in VIII. Vasa deferentia (figure 12C: vd) about 5 m m wide, longer than atria. Atria (figure 12C: a) tubular, 120–175 m m long, 17–19 m m wide; ental part of ampullae somewhat dilated but not thin-walled. Prostatic pads (figure 12C: ppd) somewhat triangular, 34–44 m m long. Prostate gland (pr) small, with irregular to round nuclei, latter maximally 7 m m long, 6 m m wide. Sperm sac inconspicuous. Egg sac in XI. Spermathecae (figure 12B) small; ducts 25–30 m m long, maximally 29–31 m m wide, with wide ectal vestibules; ampullae spherical, 35 m m long, maximally 35–40 m m wide, with sperm scattered or as bundles in lumina.

Remarks. This species was originally described from Puerto Rico (Erséus and Milligan, 1988), and then reported from Belize (Erséus, 1990b). The new material conforms well to the previous descriptions, except that its sperm are sometimes scattered in the spermathecae; they were originally stated to be in bundles only (Erséus and Milligan, 1988). In addition, we here supplement the description with details regarding the beginning of chloragogen cells, and the nature of the blood plexus associated with the oesophagus.

In one of the specimens, the irregular blood plexus is present also in the posterior part of the oesophagus in segment VIII. A similar situation was observed in some specimens of Doliodrilus diverticulatus (see above). Thus, the presence or absence of an irregular oesophageal blood plexus around segment IX may be an intraspecific variation.

Distribution and habitat. New Caledonia (new record), Belize, and Puerto Rico Intertidal and subtidal, mud and sandy mud; at least in Puerto Rico subject to fluctuating salinities.