Malagabdella niarchosorum, BORDA, 2006

BORDA, ELIZABETH, 2006, A Revision of the Malagabdellinae (Arhynchobdellida: Domanibdellidae), with a Description of a New Species, Malagabdella niarchosorum, from Ranomafana National Park, Madagascar, American Museum Novitates 3531 (1), pp. 1-16 : 7-9

Malagabdella niarchosorum , new species

Figures 8–15

TYPE MATERIAL: Holotype, specimen fixed in 95% ethanol, Madagascar — Parc National Ranomafana in Talatakely (selectively logged, low montane forest; MG02-05 ), March 5, 2002. Collected by Mark Siddall , Elizabeth Borda , Evon Hekkala , Clara Imboule, and Raina Rakotondriany ( AMNH 5285 , Annelida). Paratypes (N 5 2), one specimen fixed in formalin, dissected, same collection data as holotype ( AMNH 5287 , Annelida). One specimen fixed in 95% ethanol, Parc National Ranomafana, on trail between Talatakely and Vatoharanana ( MG02-06 ), March 5, 2002, collected by Mark Siddall and Elizabeth Borda, ( AMNH 5286 , Annelida).

DIAGNOSIS: Male pore in XI b5/b6; Female pore XII b5 (anterior); four complete annuli between gonopores; XXIV incomplete fourannulate; nine annuli between XXIII a2 and anus; oviducal glandular sac absent; muscular vaginal tube present. Prehensile lobe present.

DESCRIPTION: Dorsum with dark brown to black background field, wide beige medial chain-link band, each link with darker field at center, approximately five annuli per link. Medial chain becomes continuous light field bordered with dark brown to black paramedial lines in posterior series. Paramedial dorsal light brown to white diamond-shaped patches at approximately the same position of every other chain-link of medial band. Dorsolateral light spots on sensillae of a2. Dark spots found along lateral margins, against light background that continues ventrally. Venter, light background with dark brown to black mottling. Annular papillae, present (figs. 8, 9).

Duognathous, monostichodont jaws. Cephalic somites with five pairs eyespots, one on each of II, III, IV, V, and VI. Somites II, III, and IV uni-annulate, V and VI two-annulate and three-annulate, respectively, VII threeannulate. Midbody somites, VIII–XXIII, five-annulate. Nephropores, lateral, in furrow of b2/a2 of each somite, first nephropore observed at IX b2/a2. Posterior somites, XXIV incomplete four-annulate (b6 converges with b5 along the anterio-lateral margin of the respiratory auricle) and XXV–XXVII uni-annulate (fig. 10). Nine annuli (dorsally) between XXIII a2 and anus. Posteriolateral respiratory auricles, bilobed, and formed along the lateral margins of XXIV b5 to XXII (fig. 10). Caudal sucker, ventral, with 57 friction rays ventral on sucker. Prehensile lobe, present (fig. 11).

General organization and regional morphology of male and female reproductive systems, not typical haemadipsoid (figs. 12– 15). Male genital pore opens at the furrow of XI b5/b6 and female genital pore opens anteriorly in XII b5 (or a2/b5) (fig. 12). Gonopores separated by four complete annuli. Median reproductive system micromorphic (fig. 13). Median male reproductive system found entirely in XI (fig. 14). Male atrium, narrow, recurves anteriorly at XII. Short ejaculatory ducts exit the male atrium laterally in XI and give rise to small, globular ejaculatory bulbs in XI. Tightly coiled epididymes arise from ejaculatory bulbs, each twice the size of an ejaculatory bulb and recurved anteriad at XII. Median female reproductive system found entirely in XII (fig. 15). Single pair of globular ovaries, posteriorly directed in XII, with thin-walled oviducts that converge into common oviduct. Common oviduct is tightly coiled ventrally and inserts into a simple, muscular, vaginal tube. Vaginal tube recurves anteriad at approximately XIII, with tube widening anteriorly and terminating in bulb at the insertion point of the gonopore at XII b5. Haemadipsoid oviducal glandular sac absent.

REMARKS: When Richardson (1975, 1978) included Haemadipsa dussumieri as a member of the genus Malagabdella , it was the only species that possessed four complete annuli between the gonopores. This was initially consistent with M. niarchosorum , n.sp. However, after the examination of the type specimen, it became obvious that M. dussumieri was distinct from M. niarchosorum , n.sp. (and from the genus Malagabdella ). For example, the position of the female pore for the type specimen of H. dussumieri is on an obviously ventrally subdivided annulus of XII b5, whereas in M. niarchosorum , n.sp., it is not subdivided. In addition, as detailed above, M. dussumieri possesses characters that deviate from domanibdellid leeches. Therefore, with the exclusion of M. dussumieri from the Malagabdellinae , M. niarchosorum , n.sp. is distinct from all other members of the genus based on external coloration and patterns, the characteristics of the male and female reproductive systems, the position of the gonopores, and the posterior annulation series, but inclusive in the Malagabdellinae based on somital annulation pattern and the possession of 57 friction rays ventrally on the caudal sucker.

ETYMOLOGY: This species is named after the Niarchos family in light of their generosity in funding this expedition. Without their support, the rediscovery of known species from Madagascar and the opportunity to describe another endemic species would not have been possible.

Figures

Figs. 8–15. Malagabdella niarchosorum, n.sp. 8. Dorsal view of color patterns showing mid-dorsal ‘‘chain-link’’ band and dark brown to black background field with light brown to white diamond-shaped patches (paratype). 9. Ventral view showing light background field with dark brown to black mottling, especially in the anterior region. 10. Dorso-lateral view of the posterior somital annulation series, position of the nephropores (n) and the respiratory auricle (au). 11. Ventral view of the caudal sucker showing 57 friction rays and prehensile lobe (phl). 12. Ventral view of the anterior somital annulation series and the positions of the male (Oi) and female (♀) gonopores, with four complete annuli between gonopores. 13. Male and female reproductive systems showing the male atrium (a), ejaculatory bulbs (eb), epididymes (e), female paired ovaries (o), common oviduct and vaginal tube (vt). 14. Male reproductive system exhibiting a narrow