Description

Body firm, muscular, with constant width in caudal direction, dorsoventrally compressed, BL 22.64–36.73 mm, BW 4.47–9.82 mm (Fig. 2a). Caudal sucker elliptic, CL 3.94–6.26 mm, CW 4.11–7.17 mm (Fig. 2b).

Annulation

Somite I completely merged with prostomium (Fig. 3a). somites II and III unite together, forming 1 annulus (Fig. 3a, b). Somite IV biannulate, (a1 + a2) > a3; in KUZ Z703, (a1 + a2) with slight dorsal furrow (Fig. 3a, b). Somite V biannulate, (a1 + a2) = a3 (Fig. 3a, b); in KUZ Z700 and Z703, (a1 + a2) with slight dorsal furrow. IV a3–V a3 unite altogether, forming posterior margin of oral sucker (Fig. 3c). Somite VI dorsally triannulate/ventrally biannulate, a1 = a2 = a3/(a1 + a2) > a3 (Fig. 3). Somite VII triannulate, a1 = a2 = a3 (Fig. 3). Somite VIII quadrannulate, a1 = a2 = b5 = b6 (Fig. 3). Somites IX–XXIII quinquannulate, b1 = b2 = a2 = b5 = b6 (Figs 4, 5). Somite XXIV quadrannulate, b1 = b2 = a2 = a3 (Fig. 5a). Somite XXV triannulate, a1 = a2 = a3 (Fig. 5a); XXV a1 (KUZ Z702), a2 (KUZ Z703), or a3 (KUZ Z700 and Z701) being last complete annulus on venter. Somite XXVI biannulate, (a1 + a2) = or > a3 (Fig. 5a); in KUZ Z701 and Z703, (a1 + a2) with slight dorsal furrow. Somite XXVII uni- (KUZ Z702) or biannulate (Fig. 5a). Anus at last annulus of XXVII (KUZ Z700) or behind XXVII (Fig. 5a).

Gonopores

Male gonopore in XI b5/b6 (Fig. 4). Female gonopore in XII b5/b6 (Fig. 4). Gonopores separated by 5 annuli.

Sense organs

Eyes 5 pairs, in parabolic arc; 1st and 2nd pairs on II + III, 3rd pair on IV (a1 + a2), 4th pair on V (a1 + a2), and 5th pair on VI a2 (Fig. 3a, b). Sensillae, papillae undeveloped.

Nephridiopores

In 17 pairs, one each situated ventrally at posterior margin of VIII a1 and b2 of each somite in IX–XXIV (Figs 3c, 4, 5b).

Digestive tract

1 median longitudinal furrow on ventral surface of oral sucker (Fig. 3b). 3 jaws situated in oral cavity, one dorsal and two ventrolateral, each jaw bearing numerous salivary papillae. Monostichodont: each jaw bearing 30–46 diminutive teeth. Pharynx reaching to IX b2/a2–a2/b5. Crop reaching to XX b2/a2, bearing 22 pairs of crop caeca: 1st pair IX; 2nd and 3rd in IX and X; 4th and 5th in X and XI, 4th larger than 5th (4th > 5th); 6th and 7th in XI and XII, 6th > 7th; 8th and 9th in XII and XIII, 8th > 9th; 10th and 11th in XIII and XIV, 10th > 11th; 12th and 13th in XIV and XV, 12th > 13th; 14th and 15th in XV and XVI, 14th > 15th; 16th and 17th in XVI and XVII, 16th > 17th; 18th and 19th in XVII and XVIII, 18th > 19th; 20th and 21st in XVIII and XIX, 20th > 21st; 22nd being post-crop caeca, in XIX b2–a2 to XXV a2–a3. Intestine reaching to XXII/XXIII. Rectum simple tubular.

Male genital organ

Testisacs 8 or 9 pairs (Fig. 6): 1st pair in XIII b5–XIV b1; 2nd pair in XIV b5–XV b1; 3rd pair in XV b5–XVI b1; 4th pair in XVI b5–XVII b1; 5th pair in XVII b5–XVIII b1; 6th pair in XVIII a2–XIX b1; 7th pair in XIX b5–XX b1; 8th pair in XX b5–XXI b1; 9th pair in XXI b5–XXII b1. Paired epididymides small, globular; right epididymis in XI a2–XII b2, left epididymis in XI a2–XII b1 (Figs 6, 7). Ejaculatory bulb absent. Ejaculatory ducts folded reaching to anterior end of male atrium (Fig. 7). Atrium continuous with penis sheet (Fig. 7). Penis sheet reaching to XII a2–b2, then turning anteriorly to male gonopore, U-shaped (Figs 6, 7).

Female genital organ

Pair of ovisacs globular, in XII b5–XIII b1 (Figs 6, 8). Oviducts short, borth oviducts converging into common oviduct in XII b5–XIII b1 (Fig. 8). Common oviduct slightly folded, descending to female vagina (Fig. 8). Vagina ellipsoid, straight, directly descending to female gonopore (Fig. 8).

Colour

When alive, dorsal surface uniform reddish brown (Fig. 9); ventral surface paler than dorsal surface; both lateral marginal stripes orange in VI a3 to XXVI (a1 + a2)–a3. In preservative, colour slightly faded (Fig. 2).

Common Names

Taxonomic Hierarchy

Kingdom: Animalia

Phylum: Annelida

Class: Clitellata

Order: Arhynchobdellida

Family: Praobdellidae

Genus: Limnatis

Species: Limnatis paluda (Tennant, 1859) Tennant, 1859