Erpobdella testacea (Savigny, 1820)

Ahmed, Raja Ben, Bielecki, Aleksander, Cichocka, Joanna M., Tekaya, Saïda, Gorzel, Małgorzata & Harrath, Abdul Halim, 2013, Erpobdellid leeches (Annelida, Clitellata, Hirudinida) from Tunisia: New records with the description of a new Trocheta species, Zootaxa 3681 (4), pp. 440-454 : 441-443

Erpobdella testacea (Savigny, 1820)

Material examined. 325 specimens collected in: Elkhirba dam, Bizerte (37°16'354” N, 10°09'552” E), Port Prince dam, Cap Bon, Korbus (36°51'162’’ N, 10°39' 404’’ E), Lebna dam (36°44'326'' N, 10°55'255'' E) and Marsh in Sejnen, Bizerte (37°03’ N, 09°13’ E).

Description of examined specimens. The length of narcotized and preserved specimens can reach 40 mm; the width at mid-body region is up to 3 mm. The anterior sucker is longitudinally elliptical and the posterior sucker is circular. The dorsal surface of the living specimens is reddish brown in colour with minuscule darker specks situated dorsally ( Fig. 3 a). The ventral surface is brighter than the dorsal ( Fig. 3 b). The mid-body segment consists of five equally long annuli. Pharyngeal stylets are absent. The head has four pairs of eyes. In the majority of examined specimens the gonopores are separated by 4 annuli with the occasional occurrence of variation in their position. In fact it may reach in some specimens 4.75 annuli.

The male reproductive system consists of numerous and globular testes that form voluminous and grape-like testisacs present on each side of the nerve cord and reach close to the posterior sucker. The vasa deferentia are about 7 ns long and they run from XII to XIX ganglia. They are located on the latero-ventral sides and connected to the atrium with the two ejaculatory ducts. The latter forms a loop, which is located in front of ganglia XI. The wide male atrium is 0.5 neurosomite (ns) in length and is located almost half way between the ganglia XI and XII. The atrium is small and the cornua are greatly expanded forming obtuse angle between them. They bend towards each other rather than to the ventral side. The bursa is relatively big ( Fig. 4 a, b). The female reproductive system consists of two symmetric, U-shaped ovisacs situated on either side of the nerve cord. The ovisacs begin two-third of the way between the ganglia XII and XIII and end half way between the ganglia XV and XVI. They are connected to the pocket by oviducts.

Ecology and distribution. The occurrence of E. testacea in Tunisia is restricted to lowland stagnant waters (50–65 m ASL). To date this species had been recorded from three reservoirs in the north of the country and from a small marsh. In the Lebna dam E. testacea is present in a large number all year round.

Erpobdella testacea is a Palearctic species. In the Mediterranean region it is present in northern Italy and Greece ( Nesemann 1997) and northern Tunisia ( Ben Ahmed et al. 2008). It was recorded in Croatia, Montenegro, Bosnia and Herzegovina ( Sket 1968).

Remarks. While our specimens show a variation in the distance between gonopores which may reach 4.3–4.7, Agapow and Bielecki (1992) found a constant distance of 4 annuli between gonopores in the specimens studied in Poland. In contrast, Manoleli (1972) mentioned that in the majority of specimens examined in Romania, gonopores are separated by 3.5 annuli.

Figures

FIGURE 3. Photos of live erpobdellid specimens.; a – b: E. testacea; c – d: D. punctata punctata; e – f: D. punctata maroccana; g – h: T. africana; D. F—dorsal view (this aspect looks brighter than the ventral one because of the uneven illumination conditions); V. F—ventral view; Scale bar: 0.6 cm.

FIGURE 4. Ventral, dorsal and lateral views of male atria of mature specimens: a – c: E. testacea; d – f: D. punctata punctata; g – i: D. punctata maroccana; j – l: T. africana; m – o: T. tunisiana n. sp.