Helobdella nununununojensis, SIDDALL, 2001

SIDDALL, MARK E., 2001, Hirudinea from the Apolobamba in the Bolivian Andes, Including Three New Species of Helobdella (Clitellata: Hirudinea), American Museum Novitates 3341, pp. 1-15 : 5-7

Helobdella nununununojensis , new species

Figures 16–24

HOLOTYPE (figs. 16, 17): Free­living under rocks in bofedales and slow moving streams of Ñuñuñuñuñoj in Pusupunku at 3870 m (UU99–40, fig. 3), in Ulla Ulla National Fauna and Biosphere Reserve , Departmento La Paz, Bolivia, 14°47'09"S, 69°02'46"W, 3 November 1999, hand collected by M. Siddall; (deposited in Colleccion Boliviana de Fauna, La Paz, Bolivia, uncataloged); body length 14.5 mm, maximal width 3.1 mm, with approximately 20 juveniles attached to venter inside membranous ‘‘cocoon’’, fixed in 10% formalin, stored in 70% ethanol.

PARATYPES: One dissected adult ( AMNH 4232 , Annelida), eight adults (deposited in Colleccion Boliviana de Fauna, La Paz, Bolivia, uncataloged), and eight additional adults ( AMNH 4233 , Annelida ) with and without broods all fixed in 10% formalin from the same locality UU99–40 as above, hand collected by M. Siddall on 3 November 1999. Eleven adults (deposited in Colleccion Boliviana de Fauna, La Paz, Bolivia, uncataloged), and eleven additional adults ( AMNH 4234 , Annelida) with and without broods, all fixed in 95% ethanol from the same locality UU99–40 as above, hand collected by M. Siddall on 3 November 1999. One sectioned sexually mature, fixed in 10% formalin, all mounted on 30 glass slides ( AMNH 4235.1 through 4235.30 , Annelida). Eggs from one adult fixed and stored in 95% ethanol held at‾80°C ( AMNH 100952 , Frozen Tissue Collection) .

Additional material includes one specimen from locality UU99–6 3750 m 14°44'33"S, 69°01'10"W below cataracts in Valle Tojoloque (fig. 1) hand collected by M. Siddall on 21 October 1999 fixed in 10% formalin (deposited in Colleccion Boliviana de Fauna, La Paz, Bolivia, uncataloged), and another from this same locality (UU99–6) fixed and stored in 95% ethanol held at ‾80°C ( AMNH 100950 , Frozen Tissue Collection) .

FORM (figs. 16–20): Body thin and lanceolate, distinctly broadened from XVI a3 through XX a3 (figs. 16–18) especially in live state; somites I–V uniannulate, VI– XXIV triannulate, XXV biannulate, XXVI and XXVII uniannulate; dorsum convex, without papillae; all annuli have pronounced deep furrows to the extent that the lateral margins have a sawtooth appearance (figs. 18, 19); venter flat to concave, without papillae, and, depending on reproductive status, with a distinct groove (fig. 19) along the midline from XXIII through XXIV; anterior sucker oval; mouth pore terminal, not central; caudal sucker circular, deeply concave, directed subterminal to ventrad in relaxed state (fig. 17), approximately half of the width of posterior somites. There is no chitinoid scute and there are no visible glands, however, some specimens fixed in ethanol exhibited a swelling on VIII a1 (fig. 20). Histological sectioning revealed a muscularized pad in the middorsal region of VIII a1 but no glandular tissue whatsoever.

EYES (fig. 20): One pair, punctiform, well separated, at II/III.

COLOR AND PATTERN (figs. 16–20): Dorsum with irregular longitudinal arrays of gray to brown chromatophores but no definite lines or bands. Venter much lighter with irregularly arranged chromatophores on either side of the midline.

REPRODUCTIVE SYSTEM (figs.19, 21): Male and female gonopores separated by one annulus, male at XII a1/a2, female at XII a2/ a3; six pairs of testisacs at XIII/XIV through XVIII/XIX; sperm ducts reach to XIX, atria piriform, directed anterolaterally, sperm ducts empty into atria dorsally; ovisacs straight and long, reaching to XVII.

ALIMENTARY TRACT (figs. 22, 23): Proboscis in membranous sheath, base at XIII; salivary cells arranged in a compact mass only in XXIII, ductules of the latter forming a bundle inserting into base of proboscis; oesophagus simple, not recurved; no gastric chambers or digitiform caeca in midbody somites; postcecae (diverticula) in XIX only (fig. 23); intestine from XIX/XX with four lobes; anus at XXVI/XXVII.

ETYMOLOGY: Reflects the type locality Ñuñuñuñuñoj (a Quechua placename, ‘‘ The Place of Very Bare Breasts’ ’, from Ñuñu meaning nipple), a bowl at the top of Valle Pusu Punku. The species name, thus, should be pronounced nyue­nyue­nyue­nyue­nyoehen­sis.

REMARKS: This species was found exhibiting a wholly unique brooding behavior (fig. 24) in that adults with eggs in various stages of development would invariably be folded in half so as to enclose their young. Moreover, this specialized brooding behavior is accompanied by a distinct broadening from XVI a3 through XX a3 where the eggs are held in a pocket on the venter (fig. 17). In adults that had eggs (as opposed to hatched juveniles) attached, there was a distinct trough in the ventral midline (fig. 19) running directly from the female gonopore to XVII. This groove also was visible histologically. It is tempting to think of it as a bowling lane for eggs being passed back to the brooding somites. The possession of the very pronounced sawtooth­like annuli is characteristic of Helobdella godeti and Helobdella columbiensis , both of which might be expected to occur in the area in as much as the former was discovered at 5140 m in Peru and the latter at 2400 m in Colombia ( Weber, 1913, 1915, 1916a, 1916b). Helobdella columbiensis apparently resembles Helobdella triserialis in having very distinct lines on its dorsum. In addition, H. columbiensis has a long tapering ‘‘neck’’ between the clitellum and the cephalic somites and the oral sucker is reportedly exceedingly small ( Weber, 1913, 1915). Helobdella godeti , which also has short postcaeca, nonetheless has the full six pairs of gastric caeca and a distinct chitinoid scute on VII a1, a2. The lack of gastric caeca and the presence of short postcaeca in XIX or XIX to XX is more a characteristic of H. elongata , H. michaelseni , H. ampullariae , and H. similis placed collectively in the genus Gloiobdella by Ringuelet (1978b; see also Sawyer, 1986). Much like H. nununununojensis , Helobdella michaelseni and H. obscura have no caeca whatsoever, including no postcaeca ( Blanchard, 1900; Weber, 1915; Ringuelet, 1944b), whereas H. ampullariae and H. similis do have postcaeca in XIX only ( Ringuelet, 1942 a, 1942b, 1945). These species, like H. elongata in North America, are completely colorless even when viewed live ( Ringuelet, 1942 a, 1942b, 1944 a, 1944b, 1945). Moreover, both have their eyes situated on IV (i.e., on the fifth annulus), H. ampullariae has only four pairs of testisacs ( Ringuelet, 1945) and the sperm ducts of H. similis reach only to XV/XVI, and both of these have diffuse salivary tissue. Perhaps the most similar known species is Adaetobdella cryptica (see Ringuelet, 1978b) in the genus Ringuelet erected for those species of Helobdella possessing compact salivary glands. Although the cream­colored Adaetobdella cryptica has the short postcaeca, its ovaries reach only XV and it possesses five pairs of testisacs whereas H. nununununojensis has the more typical six.

Figures

Figs. 16–24. Helobdella nununununojensis, n. sp. 16. Dorsal surface of the holotype. 17. Ventral surface of the holotype with attached brood of hatchlings. 18. Venter showing the broadened brood pouch from XVI through XX. 19. Venter showing the male (m) and female (f) gonopores as well as the central egg­bowling trough (arrowhead) exhibited by adults in the early stages of brooding. 20. Anterior of an adult demonstrating the aglandular nuchal pad. 21. Median reproductive apparatus with the tip of an oviduct (o) at XVII and the longer sperm ducts reaching XVIII/XIX. 22. Anterior digestive system with the proboscis (p) having two glandular salivary masses (arrowheads) at its base in XIII. 23. Posterior digestive system with the short postcaeca (arrowheads) in XIX only and the four pairs of intestinal caeca (i). 24. Typical brooding attitude of this species.