Helobdella europaea Kutschera, 1987

Lai, Yi-Te, Chang, Chih-Han & Chen, Jiun-Hong, 2009, Two new species of Helobdella Blanchard 1896 (Hirudinida: Rhynchobdellida: Glossiphoniidae) from Taiwan, with a checklist of hirudinea fauna of the island, Zootaxa 2068, pp. 27-46 : 37-40

Helobdella europaea Kutschera, 1987 new record

( Fig.5 & Fig. 6 )

Helobdella striata Kutschera, 1985

Helobdella europaea Kutschera, 1987

Helobdella papillornata Govedich et Davies, 1998 Helobdella europaea Kutschera, 2004

Helobdella europaea Siddall et Budinoff, 2005

Material exmined: L00048, L00051, L00058, L00068, L00069, L00095 -A, and mounted specimen SLD0016L&R, SLD0017L, SLD0022L&R, SLD0023L&R. Deposited in the Invertebrate Zoology and Cell Biology Lab, Department of Life Science in National Taiwan University, Taipei. Underneath submerged stone in Guandu Plain, Taipei, Taiwan, collected by Yi-Te Lai from Mar 2003 to date.

Diagnosis: Externally, H. europaea can be easily recognized with the five rows of distinct black-tipped papillae of the dorsum. Dorsal pigmentation arranged in numerous longitudinal dark gray stripes is an important character of H. europaea as well. No nuchal scute present.

Form: Body length 10–25 mm, maximum body width 4–7 mm, anterior sucker diameter 0.8– 1 mm, posterior sucker diameter 1–2 mm. Body ovate-lanceolate, moderately flattened, posterior half body much wider than tapering cephalic end. Dorsum arched; venter flat or slightly indented. Cephalic sucker triangular, proboscis pore in anterior part of cavity. Posterior sucker circular, diameter almost equal to half of maximum body width, venter flat, directed ventrally.

Color and pattern: Dorsum fawn; pigmentation arranged in numerous longitudinal light and dark gray lines and stripes; the two median lines most conspicuous and close together, from segment II–III till posterior sucker; whereas the submarginal and marginal lines more inconspicuous. White spots appeared regularly and interrupted the straight lines, hence the two median lines presented as a chain in particular. Venter without any dots or spots.

Eyes: One pair of punctiform to triangular eyes in III (3rd annulus).

Annulation: Body totally 67 annuli. I and II fused together as one annulate. III uniannulate. IV biannulate. V–XXIV midbody somite, triannulate with a2>a1&a3. XXV and XXVI biannulate with (a1a2)>a3. XXVII uniannulate. Anus on the somite XXVII (67th annulus).

Papillation: Dorsum with five rows of conical, black-tipped papillae; one median row and two rows on each side submarginally. The middle row of papillae from VII–XXV; while the submarginal and marginal rows of papillae from IX–XXIV and XVII–XXII respectively. Dorsum of posterior sucker with few scattered flattened papillae. Venter smooth.

Gonopores: Gonopores separated by one annulus, male gonopore in the groove between somite XI a2/a3 (24th/25th annulus), female gonopore in the groove between somite XI a3 and XII a1 (25th/26th annulus).

Digestive system: Pharyngeal proboscis long, with diffuse salivary glands distributed aside the root of the pharynx in XI and backward to XVI. Crop in XV–XIX, with five pairs of slightly complex and branched caeca; each pair of caeca larger, more complex and lobate than the former one; all caeca stretched more or less backward, especially the last pair of caeca stretched and elongated backward to XXIII. Four pairs of large and conspicuous intestinal caeca in XX–XXIII. Hind gut saccate, rectum oblique and tapered towards anus.

Male reproduction system: Five pairs of testisacs intersegmentally arranged at XIV/XV–XVIII/XIX; vas deferens enters sperm duct in XIII, expands into seminal vesicle with S-shaped loop. Ejaculatory duct almost straight, with the same wide and proceeds obliquely outward and forward up to XI/XII. Terminal end of ejaculatory duct turning inwards towards atrial cornu at XI/XII, Cornua muscular, strongly divergent, nearlyovate in dorsal view. Atrium short and indistinct.

Female reproduction system: one pair of long, thick, and straight ovisacs directed caudally. Oviducts joined into short and indistinct atrium in XII.

Habitat: H. europaea was only recorded in slow streams, irrigation ditches, drainage ditches and polluted open sewers in the Guandu Plain in Taipei. They were found attached underneath submerged or semisubmerged objects, including stones, woodblocks, and plastic rubbish. They could also be found on the concrete walls of ditches. Occasionally H. europaea were collected from the surface of shells and mantle cavity of apple snails, P. canaliculata .

Prey or host: aquatic snails.

Remarks: H. europaea is similar to H. triserialis and H. cordobensis , and has been recognized as a member of the H. triserialis complex with the latter two species because of the resemblance in their external and internal characters (Siddall & Budinoff 2005). The use of DNA barcoding for identifying H. europaea has been variously documented ( Siddall & Borda 2003; Kutschera 2004; Pfeiffer et al. 2004; Siddall & Budinoff 2005; Bely & Weisblat 2006), and this technique may be the best way to identify this species.

It is the first time that H. europaea was recorded in the Sino-Japanese region and also in Taiwan. Because of the conspicuous conical and black-tipped papillae, the misidentification of H. europaea as another species is hardly possible. Because H. europaea was found in an easily accessible habitat, such as rice paddies and irrigation ditches, it should have been recorded before. Since leeches with strong and black-tipped papillae have never been recorded in Taiwan ( Oka 1910, 1923, 1925, 1928 a– c, 1929 a – c, 1930, 1931, 1934; Takahashi 1931, 1933, 1934 a – b, 1935), H. europaea likely invaded the island in these decades.

Figures

FIGURE 5. External morphology of Helobdella europaea. The scale indicates 1 mm.

FIGURE 6. Internal morphology of Helobdella europaea. Roman numerals of X and XX indicate the orders of the ganglia. an. Anus; atr. Atrium; br. Brain; cr. Crop and crop caeca; ejc. Ejaculatory duct; g. Ganglion; int. Intestine and intestine caeca; mth. Mouth; ov. Ovary; prb. Proboscis; rt. Rectum; salg. Salivary gland; te. Testisacs.