Enchytraeus sp.3

Nagy, Hajnalka, Dózsa-Farkas, Klára & Felföldi, Tamás, 2023, New insights into the Enchytraeus albidus complex (Annelida, Enchytraeidae), with the description of three new species from seashores in Italy and Croatia, European Journal of Taxonomy 870, pp. 107-145 : 31-32

Enchytraeus sp.3 from Kerguelen Islands

Material examined

KERGUELEN ISLANDS • 5 specs; Ile Guillou Island ; ID 260 to 261 , slide No. 3035 to 3037 ; ELTE .

Description

Based on the few specimens in imperfect condition, Echytraeus sp.3 from Kerguelen Islands is very similar morphologically to E. albidus s. str.

MEASUREMENTS. Body length 10–13 mm, segment number 44–54, 610–660 μm wide at clitellum, fixed.

CHAETAE. Chaetal formula: 3–2,3:3,4–2,3. 87–95 μm × 8 μm in ventral bundles, 77–80 μm × 7.5 μm in lateral bundles preclitellarly and 77–80 μm × 7 μm in ventral bundles and 62–70 μm × 5 μm in lateral bundles posteriorly.

DORSAL VESSEL. from XIII–XIV.

COELOMOCYTES. 31–42 μm long.

SPERM SACS. Large sperm sacs, located in X–XI.

SPERM FUNNEL. 375–550 μm long, about 4 × as long as wide, fixed.

SPERMATOZOA. About 60 μm long, heads 18 μm. Sperm duct about same wide in all length (23–30 μm wide).

MALE COPULATORY ORGANS. Male glands multiple: one larger rounded primary bulb (80–100 μm, fixed) and numerous smaller glands.

SPERMATHECAE. Ectal duct of spermatheca with glands around duct, not only at the orifice. Ampulla with one diverticulum (about 210 μm long, fixed).

Distribution and habitat

Guillou Island, Kerguelen Islands, under a small clump of Poa kerguelensis .

Results of molecular analysis

Results of molecular analysis corroborated that E. adrianensis sp. nov., E. andrasi sp. nov. and E. andrasiformis sp. nov. are new, distinct species, since the sequences obtained from the examined individuals clearly separated in the phylogenetic trees ( Figs 10–12 ). Our study also provided new reference sequences for E. albidus s. str., E. irregularis , E. krumbachi , and it provided sequences for further unnamed taxa within the E. albidus group (E. sp.2 and E. sp.3). Enchytraeus andrasi sp. nov. and E. andrasiformis formed distinct lineages, they were placed outside the clade of the E. albidus complex in the phylogenetic trees. The p-distances between the COI sequences of E. andrasi and E. andrasiformis are 16.8–17.6%, the H3 distances between them are 3%. The COI distances between E. andrasi and the members of E. albidus complex (including E. adrianensis ) are 15.9–20.6%, the H3 distances between them are 5.4–8.5%. The intraspecific COI distances between specimens of E. andrasi are 0–1.8%. There are no intraspecific differences between the H3 sequences of E. andrasi individuals. The COI distances between E. andrasiformis and the species of E. albidus complex (including E. adrianensis sp. nov.) are 15.6–20.3%, the H3 distances between them are 5.2–8.1%. Enchytraeus adrianensis and additional species missing from the study of Erséus et al. (2019), namely E. irregularis , E. sp.2 and E. sp.3 were placed inside the clade of the E. albidus complex. The COI distances between E. adrianensis and members of E. albidus complex are 12.8–17.8%, the H3 distances between them are 0.4–5.5%. There are no intraspecific differences between the COI and between the H3 sequences of specimens of E. adrianensis . Enchytraeus sp.2 and E. sp.3 formed one group on the gene trees. It is worth noting that the COI distance between E. sp.2 and E. sp.3 is very small (0.2%), while the H3 distance between them is bigger (2.5%), and comparable to interspecific differences in the rest of the H3 gene tree ( Fig. 11 ). Enchytraeus adrianensis appeared as the sister group of E. krumbachi in the COI and H3 gene trees, and E. irregularis appeared as the sister group of E. sp.2 / sp.3 clade in both of the gene trees ( Figs 10– 11 ). The COI distances between E. adrianensis and E. krumbachi are 12.9–13.4%, the H3 distances between them are low, 0.4–1.6%. The COI distances between E. irregularis and E. sp.2 / sp.3 clade are 12.2–12.9%, the H3 distances between them are 2.1–3.8%. According to the molecular analysis, our E. krumbachi individuals and E. cf. krumbachi CE1684 and CE1689 specimens belong to the same species. The intraspecific COI distances between our E. krumbachi and E. cf. krumbachi individuals are 0.7–3%, the intraspecific H3 distances between them are 0–0.8%. On the species tree ( Fig. 12 ), the E. albidus complex formed a distinct clade with maximum posterior probability support and contains E. adrianensis , E. irregularis and E. sp.2 / sp.3, as in the gene trees. E. adrianensis sp. nov. appeared as the sister group of E. krumbachi , E. sp.2 / sp.3 appeared as the sister group of E. irregularis . Enchytraeus andrasi and E. andrasiformis were placed outside the E. albidus complex and they appeared there as sister groups of each other. E. andrasi and E. andrasiformis clustered with E. norvegicus Abrahamsen, 1969 on the species tree ( Fig. 12 ) but with only low posterior probability support, and the latter species differs from the new species in many traits.

Figures

Fig. 10. Maximum likelihood (ML) tree of the COI gene for specimens of the Enchytraeus albidus species complex, based on 568 nucleotide positions using the General Time Reversible substitution model. Bootstrap values greater than 50 are shown at the nodes. Accession codes of sequences with collection information are given in Table 1. Scale bar: 0.05 substitutions per nucleotide.

Fig. 11. Maximum likelihood (ML) tree of the H3 gene for specimens of the Enchytraeus albidus species complex, based on 225 nucleotide positions using the Kimura 2-parameter substitution model. Bootstrap values greater than 50 are shown at the nodes. Accession codes of sequences with collection information are given in Table 1. Scale bar: 0.01 substitutions per nucleotide.

Fig. 12. Enchytraeus Henle, 1837 species tree, based on COI, H3 and 16S rRNA gene (Bayes analysis, *BEAST). Posterior probabilities greater than 0.5 are shown at the nodes. Accession codes of sequences with collection information are given in Table 1. Abbreviation: n = number of included specimens for each species. Scale bar = 0.07 substitutions per nucleotide.