Helobdella stagnalis
Abstract
Helobdella stagnalis (Linnaeus, 1758) (Figs 1; 2D) Hirudo stagnalis Linnaeus, 1758: 649 (original species description; type locality and type deposition: not known). Glossiphonia perata Johnson, 1816: 26. Erpobdella bioculata Lamarck, 1818: 296. Clepsine bioculata – Savigny 1822: 102, fig. 2. Glossobdella pulligera Blainville, 1827: 266, fig. 6. Clepsine stagnalis – Fillipi 1837: 27. Glossiphonia bioculata – Moquin-Tandon 1846: 366, fig. 16-26. Clepsine modesta Verrill, 1872: 126. Glossiphonia stagnalis – Blanchard 1894: 25. Glossiphonia (Helobdella) stagnalis – Harding & Moore 1927: 67, fig. 27. MATERIAL EXAMINED. — Uzbekistan • 10 samples; Ferghana Valley, Andijan region; 22.III.2020; Kh. Solijonov leg.; Department of Zoology and Animal Ecology, V. N. Karazin Kharkiv National University PREVIOUS RECORDS. — Central Asia • 1 sample; Samarkand region, Uzbekistan; 2.XI.1898; Retter leg. • 2 samples; Kurgaldzhin Lake in the Akmola region, Kazakhstan; 14.VI.1899; Ignatov leg. (Plotnikov 1907) • 59 samples; Ashkhabad, Turkmenistan; 9.II.1911; (Shchegolev & Shchegoleva 1951) • 7 samples; Issyk-Kul, Kyrgyzstan; 13.VII.2005; (Jueg et al. 2013). ADDITIONAL DATA. — See Appendix 1. DIAGNOSIS. — Body length at full elongation 8-20 mm, body width 6-12 mm. Body oblong-oval at rest, middle of body wider than anterior end, body slightly tapered posteriorly. During movement, the body can be stretched up to three times more than in a calm state. Body margins denticulate, better expressed in fixed specimens.Dorsal body surface smooth. Body appearing yellowish-grey when stretched and green when shortened due to the presence of dark green spots (dots) on the back surface of the body. They are smaller and more numerous on the posterior portion of the body and larger and less numerous on the anterior portion. Brown chitinous scutum located on trachelosome. One pair of clearly separated eyes. REMARK This species was recorded for the first time in the Ferghana Valley of Uzbekistan. Collected samples are small. MOLECULAR GENETIC ANALYSIS Helobdella stagnalis (Linnaeus, 1758) Helobdella stagnalis formed a distinct clade on the phylogenetic tree of the genus Helobdella (log-likelihood: –13015.5363 [s.e. 600.4929]). The Ferghana scute-bearing leech clustered with H. stagnalis, occupying a sister position to the Daghestan leech (Fig. 3; Supplementary material 1. Another sequence from Uzbekistan did not group within this clade. The Helobdella stagnalis clade consists of two major monophyletic groups that can be designated as the Northern/ Eastern Palearctic and Northern/Southern Palearctic clades to characterise their geographical distribution. The Ferghana leech was assigned to the former monophyletic group. The uncorrected genetic distance between the COI sequence of H. stagnalis from the Ferghana Valley and the other sequences of the clade of H. stagnalis is 0.0181± 0.0031. Neutrality tests were done to analyse if selection has played a role in the molecular evolution of the COI gene in H. stagnalis. The codon-based Z-test revealed purifying selection in the COI locus. Tajima’s D for the entire clade of Helobdella stagnalis does not reject the hypothesis of neutrality (Table 2).