Lumbricillus kaloensis Nielsen & Christensen, 1959

Klinth, Marten J., Rota, Emilia & Erseus, Christer, 2017, Taxonomy of North European Lumbricillus (Clitellata, Enchytraeidae), ZooKeys 703, pp. 15-96 : 27-28

Lumbricillus kaloensis Nielsen & Christensen, 1959 Fig. 9

Lumbricillus kaloensis Nielsen & Christensen, 1959: p. 100, figs 113-114; Erséus et al. 2010; Klinth et al. 2017.

Type material.

Typus amissus (Nomenclatura Oligochaetologica). Type locality: Kalø Vig, Denmark. We did not designate a neotype as we do not have material from the type locality.

Material examined.

SMNH 152733 (CE978), one mature specimen from Sweden & ZMBN 107842 (CE5412), one immature specimen from Norway. For information on specimen collection localities and GenBank accession numbers see Appendix 1.

Description.

Orange or whitish worms. Length (fixed worms) more than 2.8-3.6 mm (amputated specimens), first 15 segments 2.5-3.1 mm long, width at clitellum 0.32-0.37 mm. More than 18 segments. Chaetae slightly sigmoid (Fig. 9A). Dorsal bundles with 3-5 chaetae anterior to clitellum, 2-3 chaetae in postclitellar segments. Ventral bundles with 3-6 chaetae anterior to clitellum, 2-5 chaetae posteriorly. Each worm’s longest measured chaetae 50-60 µm long, about 3 µm wide. Clitellum extending over XII– 1/2XIII. Head pore at 0/1. Epidermis with transverse rows of gland cells.

Coelomocytes numerous, 15 µm long, round, oval, granulated. Paired pharyngeal glands present in IV, V and VI; each pair converging dorsally (Fig. 9B). Dorsal vessel originating in XIII. Nephridia observed in IX–X and possibly XIV–XV, about 110 µm long. Anteseptale small, consisting of funnel only. Postseptale oval, tapering posteriorly into efferent duct. Brain with posterior incision.

Male genitalia paired (Fig. 9D). Testes originating in XI, extending forwards into IX, in one specimen also extending backwards into XII, with testis sacs forming regular club-shaped lobes. Sperm funnels in XI, 185 µm long, 155 µm wide, making them slightly longer than wide, funnels tapering towards vasa deferentia. Most of vasa irregularly coiled in XII, 15 µm wide. Penial bulbs round, 80 µm in diameter. Ovaries in XII. No mature eggs observed.

Spermathecae (Fig. 9C) in V, spindle-shaped, without distinct ampulla, gradually widening, entally connecting with oesophagus. Sperm evenly embedded in ampulla. Spermathecae 290 µm long, 65 µm wide at widest part of ampulla. Gland cells surrounding ectal pore divided into at least three somewhat separated lobes, one lobe significantly larger than the others, whole glandular body 120 µm in diameter at its widest part. Two midventral subneural glands in XIII–XIV, 95 µm and 75 µm long, respectively.

Geographical distribution including BOLD data.

Originally described from Denmark, now genetically identified from Norway and Sweden. BIN-number: BOLD:AAU0152.

Remarks.

The specimens examined in this study match the original description by Nielsen and Christensen (1959) in the majority of the characters. Our worms were smaller than theirs, with slightly fewer chaetae (particularly in postclitellar bundles) and sperm funnels shorter in relation to their width, the latter of which could be explained by the difference between live and mounted material. We also observed two subneural glands which were not originally reported by Nielsen and Christensen. The spermathecae, despite being slightly damaged in our mature specimen, exhibit the typical large asymmetrical ectal gland subdivided into flap-like lobes, one of which is clearly larger than the others. Asymmetrical ectal glands have also been observed in L. enteromorphae von Bülow, 1957, and to some extent in L. rubidus Finogenova & Streltsov, 1978. The former can be distinguished from L. kaloensis by having sperm funnels 8 times longer than wide, and an atrium-like part where the vasa deferentia meet the penial bulbs. Lumbricillus rubidus , while having ectal glands on the spermathecae that may appear asymmetrical, does not have the glands subdivided into such clearly asymmetrical flaps as in L. kaloensis . Furthermore, L. rubidus has a more distinct musculature covering the ectal duct of the spermathecae, sometimes appearing as a muscular bulb; L. kaloensis also has a muscular coating of the duct, but it is thinner.

Lumbricillus kaloensis is genetically placed within the lineatus group. Its possible sister-group relationship with Lumbricillus sp. F (suggested by the tree in Fig. 1) is not statistically supported by the DNA data.