Hirudo tianjinensis Liu, 2022

Wang, Hao, Meng, Fan-Ming, Jin, Si-Jie, Gao, Jiang-Wei, Tong, Xiang-Rong & Liu, Zi-Chao, 2022, A new species of medicinal leech in the genus Hirudo Linnaeus, 1758 (Hirudiniformes, Hirudinidae) from Tianjin City, China, ZooKeys 1095, pp. 83-96 : 83

Hirudo tianjinensis Liu sp. nov.

Material examined.

Holotype. 20200231; Engineering Research Center for Exploitation & Utilization of Leech Resources in Universities of Yunnan Province, School of Agriculture & Life Sciences, Kunming University , Kunming ; Body length 31.2 mm, maximal body width 3.6 mm, width of anterior sucker 1.8 mm, width of posterior sucker 3.3 mm; Caobai River , Haogezhuang Town , Baodi District, Tianjin City, China; 39°36'40"N, 117°23'13"E, 5 m; collected by Zichao Liu, 19 Aug. 2020 (Figs 1 , 2 , 3 ) . Paratypes. 16 ex.; collected information same as holotype; 20200232-20200247, Engineering Research Center for Exploitation & Utilization of Leech Resources in Universities of Yunnan Province, School of Agriculture & Life Sciences, Kunming University, Kunming .

Diagnosis.

Hirudo tianjinensis can be distinguished from its congeners by the following combination of characters: blackish green dorsum with five continuous yellow longitudinal stripes; six sensillae on dorsal annulus a2 of segments VIII-XXV making dorsal golden midline notched, and two lateral blackish green dorsal line rosary; greyish green ventrum with irregular dark brown spots bilaterally; dorsum and abdomen separated by a pair of pale yellow stripes; front half of atrium wrapped by white prostate; apparent albumen gland; epididymis massive in relation to ejaculatory bulb.

Description.

Blood-feeding aquatic leech, medium body size, length 34.8 ± 3.5 mm (n = 17), maximum body width 3.7 ± 0.4 mm, width of anterior sucker 1.8 ± 0.2 mm, width of caudal sucker 3.6 ± 0.4 mm. Caudal sucker diameter slightly narrower than maximal body breadth.

In relaxed state, dorsum and abdomen flat and willow-leaf like. Blackish green dorsum with five continuous yellow stripes. Dorsal midline widest, extending from the first to the last somite. Yellow stripes separate dorsum into six blackish green longitudinal stripes of which the middle two are the widest and the lateral four are narrower. Six sensillae on middle a2 of segments VIII-XXV making middle golden stripe notched and two lateral blackish green stripes rosary. Venter greyish green with irregular dark brown spots bilaterally edged by a pair of pale yellow stripes. No visible sensillae in abdomen. Caudal sucker reddish brown, with dark dorsum and pale-colored abdomen.

Complete somite five-annulate, numbers of annuli per somite: I-III: one, IV-V: two, VI-VII: three, VIII: four, IX-XXIII: five (b1, b2, a2, b5, b6), XXIV: four, XXV: three, XXVI-XXVII: two, in total: 27 somites and 103 annuli.

Wide mouth in white anterior sucker. Jaws trignathous, one in the middle and one on each side, 55-67 horny teeth in each jaw. Five pairs of eyes almost circular or irregular shaped on annulus 2, 3, 4, 6, and 9. Fifth pair of eyes smallest and sometimes difficult to observe. Two nephridiopores in submarginal annulus b2 of each complete somite. Gonopores situated in furrow between annuli, separated by five annuli, male pore in furrow XI b5/b6 (annulus 31/32), female pore in furrow XII b5/b6 (annulus 35/36). Anus in middle dorsum between the last two annuli.

Male reproductive system: pyriform atrium large, located at venter of ganglion in segment XI; prostate white and developed, covering front half of atrium, strikingly different from its sister species H. nipponia whose prostate is almost invisible; penis sheath with a duct bent anteriorly in segment XI; epididymis massive in relation to ejaculatory bulb, tightly packed masses of ducting standing upright on either atrial side; ejaculatory bulb tapering sharply and connected to dorsal epididymis; testisacs ovoid, 11 pairs, in segments XIII-XXIII.

Female reproductive system: composed usually of one vagina, two ovisacs, and a curved duct in segments XII-XIII; vagina long, upright, and ellipsoidal with apparent albumen gland on middle surface, no vaginal duct; ovisacs ovoid, smaller than testisacs, connected to vagina via a curved common oviduct.

Remarks.

This species is frequently confused with H. nipponia due to their morphological similarities and overlapping distributions. Local villagers often mistook it for H. nipponia for therapeutic usage. However, they can be distinguished using a series of morphological characteristics such as color pattern, number of sensillae, and reproductive system morphology (Table 2 ).

Etymology.

The specific name Hirudo tianjinensis is derived from Tianjin City, a municipality directly under the central government in China, where type specimens were collected.

Distribution.

Hirudo tianjinensis was collected from Caobai River, Haogezhuang Town, Baodi District, Tianjin City, China, which flows into Bohai Sea. Water was moderately polluted. Aquatic plants and irregular pumice stones were abundant along the riverbed. This species normally hid under pumice stones. Whenever people and animals pass by, it quickly adsorbs on their ankles for sucking blood.

Figures

Figure 1. Map of geographic collecting locations for three species of Chinese leeches. H. tianjinensis and H. nipponia were collected in adjacent areas of Tianjin City, and Haemadipsa yanyuanensis was collected in Yunnan Province.

Figure 2. External morphology of H. tianjinensis holotype A dorsal and B ventral view of whole body C dorsal and D ventral view of somites X-XIV E dorsal and F ventral view of somites I-VIII G dorsal and H ventral view of somites XXIV-XXVII and caudal sucker. Abbreviations: an, anus; e, eye; fg, female gomopore; mg, male gomopore; np, nephridiopores. Scale bars: 5 mm (A, B), 2.5 mm (C-H).

Figure 3. Internal characters of H. tianjinensis A dorsal view of reproductive system B ventral view of dissected anterior sucker C ventral view of jaw. Abbreviations: a, atrium; ag, albumen gland; co, common oviduct; e, epididymis; eb, ejaculatory bulb; g, ganglion; j, jaw; o, ovisac; p, prostate; ps, penis sheath; s, sulcus; te, testisac; to, tooth; v, vagina; vd, vas deferens.