Lumbricillus sp.

Lumbricillus sp. “ Greenland ” Figure 8 View Figure 8

Material examined. SMNH 212157 View Materials ( SM135 ) , SMNH 212158 View Materials ( SM137 ) & SMNH 212159 View Materials ( SM141 ) three immature or partially mature specimens from Greenland, ZMBN 153287 View Materials ( CE35532 ) , ZMBN 153288 View Materials ( CE35576 ) & ZMBN 153289 View Materials ( CE35577 ) three immature or partially mature specimens from Svalbard. For details on collection site and GenBank accession numbers see Table S1.

Description. Length of first 16–32 segments 1.4–5.4 mm (fixed, amputated specimens); first 15 segments 1.3–2.7 mm long; width at clitellum 0.26–0.37 mm. Chaetae with ental bend, ectally straight. Dorsolateral bundles with 2–4 chaetae anterior to clitellum, 2–3 chaetae in postclitellar segments. Ventral bundles with 2–4(5) chaetae anterior to clitellum, 2–3 chaetae posteriorly. Each worm’s longest measured chaetae 55–95 µm long, about 5 µm wide. Clitellum not developed. Head pore not observed.

Coelomocytes numerous, about 10–25 µm long, round, oval or spindle-shaped, granulated with distinct nucleus. Paired pharyngeal glands present in IV, V and VI; first two, and possibly also the third pair connected dorsally ( Figure 8A View Figure 8 ). Dorsal vessel originating in X–XII. Nephridia observed in 7/8–9/10, and postclitellar segments, about (60)105–165 µm long. Anteseptale small, consisting of funnel only. Postseptale oval, tapering into posteroventral efferent duct ( Figure 8B View Figure 8 ). Brain with posterior incision.

Male genitalia only partially developed. Testes in XI, lobed, ovaries and penial bulbs in XII. Spermathecae developing in V, with pore at lateral line. No midventral subneural glands observed.

Geographical distribution including BOLD data. Only known from Greenland and Svalbard.

Remarks. Unfortunately, we found no fully mature specimens of this species, but the species tree ( Figure 2 View Figure 2 ) suggests it to be related to, but not necessarily to be regarded as a member of, the pagenstecheri group.