Chamaedrilus varisetosus, Martinsson, Svante, Rota, Emilia & Erseus, Christer, 2015

Martinsson, Svante, Rota, Emilia & Erseus, Christer, 2015, On the identity of Chamaedrilusglandulosus (Michaelsen, 1888) (Clitellata, Enchytraeidae), with the description of a new species, ZooKeys 501, pp. 1-14 : 4-7

Taxon classification Animalia Enchytraeida Enchytraeidae

Chamaedrilus varisetosus sp. n. Fig. 3

Chamaedrilus glandulosus ; Friend 1919: 174, partim.

Cognettia glandulosa ; Nielsen and Christensen 1959: 43, fig. 30, partim; Schmelz and Collado 2010: 79, partim.

Cognettia glandulosa A; Martinsson and Erséus 2014.

Holotype.

ZMBN99905, CE19052, mature, anterior part, COI barcode acc. no. KP878464, leg. Christer Erséus, Aug 10, 2013.

Type locality.

NORWAY: Buskerud, Hol, at Örtedalsåna River (S of Haugastöl), elevation 1,075 m above sea level (N60.4866°, E7.8562°).

Paratypes.

ZMBN99906, CE19818, submature, anterior part, COI barcode acc. no. KP878469; NORWAY: Hedmark, Engerdal, Nymoen at Femundelva (Trysilelva) River, at Nordre Husfloen Farm (N61.6569°, E11.8164°), leg. Christer Erséus, Aug 15, 2013. SMNH type-8723, CE19819, submature, anterior part, COI barcode acc. no. KP878470. Same collection data as for the other paratype.

Other material.

See Table 1. Twenty-seven immature specimens, of which 2 from the Czech Republic, 12 from Norway, and 13 from Sweden, all DNA-barcoded.

Etymology.

The species is named after the variation in numbers of chaetae in the lateral preclitellar bundles.

Diagnosis.

The new species can be separated from all other European species of Chamaedrilus except Chamaedrilus glandulosus s. s. by its unique combination of 3-4 pairs of well-developed secondary pharyngeal glands, two chaetae in most lateral bundles in preclitellar segments, and three chaetae in all other bundles, spermathecae with comparatively long ectal ducts, and genitalia shifted forward 3-4 segments (in relation to normal placement in Enchytraeidae ). No characters completely separate this species from Chamaedrilus glandulosus , but specimens of Chamaedrilus varisetosus are generally smaller, have shorter chaetae and smaller internal organs, and usually have a few preclitellar lateral bundles with three chaetae ( Chamaedrilus glandulosus constantly has two chaetae per lateral bundle in preclitellar segments). Furthermore, Chamaedrilus varisetosus is mainly found in moist to wet soils, whereas Chamaedrilus glandulosus is only found in aquatic habitats.

Description.

EXTERNAL CHARACTERS: Size: length of 20 anteriormost segments 2.33-4.38 mm, mean 2.89 ± 0.59 (n = 13); body width in XII 0.20-0.42 mm, mean 0.28 ± 0.07 (n = 20). Chaetae sigmoid without nodulus, 50-60 µm long, chaetal formula 2,3-(2),3:3-3; most specimens with 3 chaetae in lateral bundles of III(or IV)-V and 2 chaetae in the other lateral preclitellar bundles, but some specimens have 2 chaetae in all preclitellar lateral bundles; in sexually mature specimens, chaetae missing in the segment bearing male pores (VIII or IX). In the mature and submature specimens examined, clitellum only developed (but poorly) in the segment bearing the male pores and ½ a segment posterior and anterior to that segment.

INTERNAL CHARACTERS: Brain slightly concave posteriorly, concave anteriorly, 125-140 µm long, about twice as long as broad (Fig. 3D). Pharyngeal glands, 3-4 primary pairs; 3-4 pairs of well-developed secondary glands (Fig. 3A), secondary glands behind the last pair of primary glands sometimes missing. Dorsal blood vessel arising in XIII–XVII, rarely in XI or XVIII. First pair of nephridia present at 8/9-11/12; nephridia with efferent duct originating antero-ventrally, close to septum; anteseptale consisting of funnel only; postseptale oval, elongate (Fig. 3E). Chloragogen cells granulated, 20-30 µm long. Coelomocytes finely granulated, round to oval, approximately 20 µm long.

Seminal vesicle unpaired, distinct in all three mature/submature specimens. Other genitalia paired. Sperm funnel about 100 µm long, 40-50 µm wide; collar indistinct, 25-30 µm wide. Spermatozoa not observed on collar. Vas deferens long, with several loops, about 5-7 µm wide. Penial bulb poorly developed, about 25 µm wide, 35-40 µm long (Fig. 3B). Male pores in VIII or IX. Spermathecae paired; pores located slightly below lateral chaetae; ectal duct smooth, 225 µm long, approximately 15 µm wide; ectal gland 25-30 µm in diameter; ampulla about 150 µm long, with ectal enlargement, followed by a contraction and a tubular to oval ental chamber; no sperm observed in ampulla; ampulla not attached to oesophagus (Fig. 3C). Spermathecae entering into VI.

Habitat and distribution.

Found both in aquatic and terrestrial habitats. In freshwater found on stony bottoms in rivers, on land found in both deciduous and coniferous forest as well as in grassland soils. Known from Canada (BOLD record), the Czech Republic, Finland (BOLD record), Norway and Sweden, but may be more widely distributed in Europe and North America. Schlaghamerský’s (2013) description of Cognettia glandulosa from Michigan fits our description of Chamaedrilus varisetosus . This and Schlaghamerský’s et al. (2014) records from Minnesota and Wisconsin are likely to refer to the same species.

Biology.

Parthenogenetic reproduction more limited in time (maturing specimens found in August in Norway) than fragmentation (observed in May-September in Sweden and Norway). Worms with regenerating tails and/or heads rather frequent. This species may correspond to the population studied by Christensen (1959), in which the number of mature worms was high for a short period during the autumn. The variation in number of the lateral chaetae corresponds to that given in the diagnosis by Nielsen and Christensen (1959).

Remarks.

This species is represented in BOLD by BIN: AAT9501.