Trocheta africana Nesemann and Neubert, 1994

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 : 444-447

Trocheta africana Nesemann and Neubert, 1994

Material examined. 97 specimens collected in: National Parc El Faïja (36°30’172” N, 08°19’081” E), Aïn Soltane, Jendouba (36°31’261” N, 08°20’151” E), river elFeïja (36°48’631” N, 08°30’771” E).

Description of examined specimens. The length of preserved specimens reaches up to 70 mm and the width is around 6 mm. Both anterior and posterior suckers are transversally elliptical. The caudal sucker of preserved specimens is narrower than the maximum body width. Lateral keels are present. The colour of living specimens is black. Four dark narrow longitudinal stripes are visible in the smooth dorsal surface ( Fig. 3 g). The area between the inner paramedian stripes is less pigmented than the dorsal surface. The ventral surface is pale grey ( Fig. 3 h). Annulation: somites with eight annuli, the first two of which are short, followed by three longer ones and another three short annuli. Head with four pairs of eyes. The gonopores are separated by two annuli. The male pore is situated in XII b2/a2. Whereas the female one is in furrow XII b5/c11.

The male reproductive system consists of numerous globular testes that form voluminous, grape-like testisacs that reach the end of the leech body. The sperm duct has 9.75 ns in length, beginning at XII and ends close to XXII ganglion. The atrium, located at the ganglion XII, is 0.5 ns in length. The bursa is relatively wide and well rounded. The cornua are thick and curved towards the middle ( Fig. 4 j, k, l). The female reproductive system consists of a pair of well-developed and convoluted ovisacs showing anteriorly a 1.75 ns long ‘lateral’ loop and then lying medio-ventrally. The ovisacs are 3.33 ns in length, running from a ¼ part of the way between the ganglia XII and XIII until just before the ganglia XVI. From the ovisacs appear two oviducts that run ventrally.

Ecology and distribution. Presently, Trocheta africana is the only species of the genus Trocheta that has been reported from North Africa. This species prefers stagnant water or slow running rivers or brooks. It occurs mainly in the higher regions of northern Tunisia (805–868 ASL). The specimens were found attached to the underside of rocks and stones and the dead leaves of Quercus suber ( Fig. 1 g). It has been discovered in Tunisia (in a stream near Hammam Bourguiba, a mountain stream between Thibar and Téboursouk, Béja) and in Algeria.

Remarks. In the original description of T. africana made by Nesemann and Neubert (1994) the examined specimens are described as small leeches. In fact, the length of preserved specimens ranged from 15 to 28 mm. In this study, the length of examined specimens ranged from 50 to 70 mm. Notwithstanding, there is no detailed description of the ovisacs condition we believe that the specimens studied by Nesemann and Neubert (1994) were juveniles, because they were collected at the end of February. The specimens examined in the present study were collected in December and they were mature, because we could observe oocytes inside the ovisacs.

Figures

FIGURE 1. (a – f): Some sites of leech collection in Tunisia: a: Lebna Dam; b: Aïn Essaniya, Siliana; c: Aïn Soltane, Jendouba; d: Aïn Nfaja; e: National Parc ElFaïja; f: Aïn Sidi Saleh, Bizerte; g: T. africana collected from a leaf of Quercus siber; h: Dina punctata maroccanna swallowing a worm (Lumbricus. sp).

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.