Lizabdella africana, Utevsky, 2007

Utevsky, A. Yu., 2007, A new genus and species of marine fish leech (Annelida: Hirudinea: Piscicolidae) from South Africa, African Invertebrates 48 (2), pp. 41-46 : 43-45

Lizabdella africana sp. n.

Figs 1–3

Etymology. The specific name refers to Africa.

Diagnosis: Small leeches. Body cylindrical, tapered toward suckers. Segmental pigmentation present. Suckers small, anterior sucker possessing one pair of eyes. Crop tubular, without chambers. Posterior crop caeca not totally fused.Accessory glands and conductive tissue present. Clitellum with paired male pore. Lacunar system poorly developed.

Description: Small leeches, up to 7.6 mm in length. Measurements of trachelosome: length, 1.7 mm; maximum width, 0.5 mm. Measurements of urosome: length, 5.2 mm; maximum width, 0.7 mm. Body elongated, cylindrical, tapered toward suckers, indistinctly divided into trachelosome and urosome. Body surface smooth with no external pulsatile vesicles. Segmental ocelli absent. There are 6 yellowish brown bands on the trachelosome and 13 segmental bands of the same colour on the urosome.The coloration of suckers is relatively light in comparison with the body. Young specimens may be unpigmented and transparent, the preserved leeches still have numerous black starshaped cells.

Anterior sucker small, 0.2 mm in diameter (3.5 times smaller than maximum body width), indistinctly separated from trachelosome, eccentrically attached. Surface of sucker smooth, with one pair of eyes at its base, mouth-pore centrally located.

Posterior sucker small, 0.5 mm in diameter (1.5 times smaller than maximum body width and 2.5 times larger than anterior sucker), distinctly separated from urosome, eccentrically attached. Surface of sucker smooth, ocelli absent.

Annulation ( Figs 2A, 2C ). Preclitellar region of trachelosome consisting of 15 annuli. Clitellum 7-annulate, male pores between annuli 1 and 2, female pore between annuli 5 and 6, copulatory area absent, annuli 1 and 3 subdivided into additional rings. Complete somite 3-annulate. Anus separated by one annulus from posterior sucker.

Digestive system ( Fig. 2B ). Base of proboscis located at ganglion 2 of ventral nerve cord. Oesophageal diverticula and crop chambers absent. Young specimens with 5 crop chambers ( Fig. 1C ). Posterior crop chambers not totally fused with 2 fenestrae, extending to posterior-most ganglion of ventral nerve cord. Intestine bearing 2 chambers with lateral processes and rectal dilation.

Reproductive system ( Figs 2D–F ). Structured testisacs were not found. Only parenchymatous tissue without coelomic epithelium was found in place of testisacs. Seminal reservoirs not developed. Ejaculatory ducts short and loop-like, with rounded terminal portions and accessory glands present. Common atrium and bursa absent. Ejaculatory ducts opening directly on clitellum through two male pores ( Fig. 3 ). Spermatophore consisting of two separate pieces. Ovisacs short and wide, located between ganglia 6 and 7 of ventral nerve cord. Conductive tissue mass without channels connecting vagina and ovisacs. Copulatory area absent.

Lacunar system. Only ventral lacuna developed. Lacunae of testisacs and communications absent. Dorsal lacuna not found. Dorsal and ventral vessels located outside of lacunae.

Comparison: L. africana differs from all existing fish leeches in having two separate male pores. It can easily be distinguished from other South African marine leeches. Austrobdella oosthuizeni has a cylindrical trachelosome and a distinctly separated flattened urosome, larger suckers, and no eyes or segmental coloration pattern. In addition, A. oosthuizeni, in contrast to L. africana , possesses larger crop chambers and totally fused posterior crop caeca, a long bursa and a long vagina with no conductive tissue. The new species also differs from Malmiana stellata , which is characterised by the absence of integrated eyes and a segmental coloration pattern. It is not possible to compare the new species with M. stellata in detail, as internal characters of the latter are still unknown.

Holotype: AN 42 (on 4 slides). SOUTH AFRICA: Eastern Cape: Kowie estuary [33º36'S: 26º54'E], from Liza sp. , 21.x.1984, I. Paperna (NM NASU).

Paratypes: Six specimens with the same label data:AN 43 (on 4 slides) and AN 44 (NM NASU), four other specimens in NMSA.

Other material examined: SOUTH AFRICA: Eastern Cape: 64 specimens, same data as holotype ; 63 specimens, Port Elizabeth , Swartkops estuary [33º52'S: 25º36'E], 1985, I. Paperna (KhNU) .

Figures

Fig. 1. External view of Lizabdella africana gen. et sp. n.: (A, B) holotype, dorsal and lateral views; (C) young transparent specimen, lateral view.Abbreviations:E – eyes, Mp – male pores, Cc – crop chambers, Pcc – posterior crop caeca.

Fig. 2. External and internal characters of Lizabdella africana gen. et sp. n., holotype: (A) dorsal view; (B) digestive system, dorsal view (P – proboscis, C – crop, I – intestine, Ic – intestinal chambers, Rd – rectal dilation, Pcc – posterior crop caeca, F – fenestrae); (C) clitellum, ventral view, with a tubercle t that separates paired male gonopores, which are not clearly visible externally; (D) reproductive system, dorsal view (G – ganglia of ventral nerve cord, Ip – initial part of ejaculatory duct, Tp – terminal part of ejaculatory duct, accessory glands not shown, Os – ovisacs, conductive tissue not shown); (E) spermatophore; (F) reproductive system, lateral view (Ip – initial part of ejaculatory duct, Ag – accessory glands, Tp – terminal part of ejaculatory duct, Os – ovisacs, Ctm – conductive tissue mass, V – vagina).

Fig. 3. Male gonopores, transverse section in clitellum region. Abbreviation: Mp – male gonopore.