Orobdella shimadae, Nakano, Takafumi, 2011

Nakano, Takafumi, 2011, Redescription of Orobdella ijimai (Hirudinida: Arhynchobdellida: Gastrostomobdellidae), and two new species of Orobdella from the Ryukyu Archipelago, Japan, Zootaxa 2998, pp. 1-15 : 10-11

Orobdella shimadae sp. nov.

( Figs. 8 , 9 )

Diagnosis. In life, dorsal surface greenish yellow, ventral surface whitish yellow. Somite VII triannulate. Somite VIII quinquannulate. Somites IX–XXV complete sexannulate. Somite XXVI quinquannulate. Pharynx reaching to XVI. Gastropore absent. Gastroporal duct narrow, tubular, descending to XV a2. Male gonopore in XI b5/c11 or at anterior of XI c11, close to b5/c11. Female gonopore in XIII b1/b2 or at anterior of XIII b2, close to b1/b2. Gonopores separated by nine annuli. Pre-atrial loop present, extending to ganglion XI. Atrial cornua absent.

Materials examined. Holotype. KUZ Z128, mature specimen of 100.9 mm in body length, dissected, collected from in the soil along the Okuyona Forest Road (alt. 100 m, 26°49.0´N, 128°16.5´E), Kunigami, Okinawajima Island, Okinawa Pref., Japan, by Taku Shimada on April 9, 2010. Paratypes (a total of nine specimens collected from Okinawajima Island, Japan). Six specimens collected by Taku Shimada: KUZ Z125 from Kunigami on February 15, 2010; KUZ Z126, dissected, and KUZ Z127, dissected, from Higashi on April 9, 2010; KUZ Z130, dissected, from near the type locality on June 17, 2010; KUZ Z137, and KUZ Z138, dissected, from the Okuni Forest Road (26°40.2´N, 128°11.2´E), Higashi, on September 6, 2010; and KUZ Z139 from the Okuyona Forest Road around the Benoki Dam (26°47.0´N, 128°16.3´E), Kunigami, on September 7, 2010. Two specimens collected from around the Benoki Dam, Kunigami on August 24, 2010: KUZ Z131 (alt. 176 m, 26°47´20˝ N, 128°15´22˝ E), dissected, by Takafumi Nakano; KUZ Z132 (alt. 191 m, 26°47´22˝ N, 128°15´21˝ E), by Keiko Tsubokawa.

Etymology. The specific name is a noun in the genitive case formed from the Latinized name of Mr. Taku Shimada who collected many valuable specimens of this species from Okinawajima Island.

Description of holotype. Body firm, muscular, BL 100.9 mm, BW 6.3 mm ( Fig. 8 ). Caudal sucker ventral, oval, its diameter slightly smaller than maximum body width ( Fig. 9 D). In life, dorsal surface greenish yellow, ventral surface whitish yellow, dorsal surface darker than ventral surface. In preservative, color faded, without any dark lines.

Somite I completely merged with prostomium ( Fig. 9 A). Somite II uniannulate, not separated from I ( Fig. 9 A). Somite III uniannulate ( Fig. 9 A). Somite IV biannulate ( Fig. 9 A). Somite V biannulate, a3 forming posterior margin of oral sucker ( Fig. 9 A, B). Somites VI triannulate ( Fig. 9 A, B). Somite VII complete triannulate, a1 = a2 <a3 ( Fig. 9 A, B). Somite VIII complete quinquannulate, a1> a2 = b5> c11 = c12 ( Fig. 9 A, B). Somite IX complete sexannulate, b1 <b2 = a2 = b5> c11 = c12. Somites X–XXV complete sexannulate, b1 <b2 = a2 = b5> c11 = c12, or b1 = b2 <a2 = b5> c11 = c12 ( Fig. 9 C–E), X b5 the first annulus of the clitellum, XIII a2 the last annulus of the clitellum. Somite XXVI sexannulate dorsally, b1 = b2 = a2 <b5> c11 = c12, quinquannulate ventrally, b1 = b2 = a2 <b5 <b6, b6 with slight furrow and the last complete annulus on the venter ( Fig. 9 C, D). Somite XXVII incomplete triannulate ( Fig. 9 C). Anus behind XXVII ( Fig. 9 C). Post-anal annulus absent ( Fig. 9 C).

Anterior ganglionic mass in VI a2 and a3. Ganglion VII in VII a2. Ganglia VIII–XXIV in a2 of each somite ( Fig. 9 H). Ganglion XXV in XXV b2; ganglion XXVI in XXVI b1. Posterior ganglionic mass in XXVI a2–b6.

Eyes three pairs, first pair dorsally in II, second and third pairs dorsolaterally on posterior margin of V (a1 + a2) ( Fig. 9 A). Nephridiopores 17 pairs, ventrally at posterior margin of a1 at VIII and b2 of each somite, at IX– XXIV ( Fig. 9 B, E). Papillae numerous, minute, hardly visible, one row on every annulus.

Pharynx agnathous, euthylaematous, reaching to XVI a2/b5. Crop tubular, acecate, in XVI a2/b5 to XXII b2. Gastropore absent ( Fig. 9 E, G). Gastroporal duct narrow, tubular but slightly bulbous at female gonopore, in XIII b1/b2 to XV b2, not joining with crop ( Fig. 9 F). Intestine tubular, acecate, in XXII b2 to XXV b1. Rectum tubular, thin-walled.

Male gonopore at anterior of XI c11, close to annular furrow of b5/c11 ( Fig. 9 E). Female gonopore at anterior of XIII b2, close to annular furrow of b1/b2 ( Fig. 9 E, G). Gonopores separated by 9 annuli ( Fig. 9 E). Testisacs multiple, two or three testisacs on each side in each annulus, in XVIII b5 to XXV a2. Epididymides absent. Ejaculatory bulbs absent. Ejaculatory ducts in XI a2 to XVII c11, coiled, widen from each junction with testisacs, narrow gradually toward each junction with atrium, with pre-atrial loop extending to ganglion XI ( Fig. 9 H, I). Atrial cornua absent. Atrium rudimentary in XI b5 and c11 ( Fig. 9 H, I). Ovisacs one pair, thin-walled, globular, in XIII a2 and b5 ( Fig. 9 H, J). Oviduct thin-walled, right oviduct crossing ventrally beneath nerve cord, both oviducts converging into common oviduct in XIII b2 ( Fig. 9 H, J). Common oviduct thin-walled, very short, directly descending to female gonopore ( Fig. 9 H, J).

Variation. Median black line on dorsal surface present or absent in preservative. Somite XXVI quinquannulate or sexannulate (KUZ Z139). Somite XXVII incomplete biannulate or triannulate; clitellum from X b5 to XIII a2. Pharynx reaching to XVI a2/b5–c11/c12. crop reaching to XXII b2–XXII a2/b5. Intestine reaching to XXIV b5/ c11–XXIV c12. Male gonopore in XI c11/c12 or at anterior XI c12, close to annular furrow of b5/c11. Female gonopore in XIII b1/b2 or at anterior of XIII b2, close to annular furrow of b1/b2. Testisacs in XVI c11–XVII a2/b5 to XXIV a2–XXV b2.

Distribution and ecology. Known from the mountain region of the northern part of Okinawajima Island in the Ryukyu Archipelago, Japan ( Fig. 1 ). Leeches were found under rocks or fallen leaves.

Remarks. Orobdella shimadae is extremely similar to Orobdella dolichopharynx in Amamioshima Island. In Orobdella shimadae , however, its gastroporal duct is reaching only to XV b2 (to XVI b 2 in O. dolichopharynx ). In accordance with the strict morphological uniqueness, Orobdella leeches from Okinawajima Island and Amamioshima Island is treated as the two distinct species, O. shimadae and O. dolichopharynx , respectively in this study.

Figures

FIGURE 1. Location of collecting localities in this study. The locality numbers are referred to as follows: the type locality of, (1) Orobdella ijimai Oka, (2) Orobdella dolichopharynx sp. nov., and (3) Orobdella shimadae sp. nov.

FIGURE 8. Orobdella shimadae sp. nov., holotype, KUZ Z 128. (A) Dorsal, and (B) ventral surface. Scale bar, 5 mm.

FIGURE 9. Orobdella shimadae sp. nov., holotype, KUZ Z 128. (A) Dorsal, and (B) ventral views of somites I – VIII. (C) Dorsal and (D) ventral views of somites XXV – XXVII and caudal sucker. (E) Ventral view of somites XI – XIII. (F) Ventral view of gastroporal duct. (G) Ventral view of female gonopore. (H) Dorsal view of reproductive system including ventral nervous system. (I) Dorsal view of male atrium. (J) Dorsal view of female reproductive system including position of ganglion XIII. Scale bars, 1 mm (A – F, H), 0.5 mm (I, J), 0.25 mm (G).