Orobdella kawakatsuorum Richardson, 1975

Nakano, Takafumi, 2012, A new species of Orobdella (Hirudinida, Arhynchobdellida, Gastrostomobdellidae) and redescription of Orobdella kawakatsuorum from Hokkaido, Japan with the phylogenetic position of the new species, ZooKeys 169, pp. 9-30 : 17-22

Orobdella kawakatsuorum Richardson, 1975 Figs 6-11

Orobdella kawakatsuorum Richardson, 1975: 42-51, figs 1, 2; Sawyer 1986: 680, 747.

Diagnosis.

In life, dorsal surface grayish blue. Somites III and IV biannulate, somites VIII–XXV quadrannulate, somite XXVI triannulate, clitellum from X b5 to XIII a2. Pharynx reaching to XIV. Gastropore conspicuous in furrow of XIII a1/a2. Gastroporal duct, simple tubular. Male gonopore in furrow of XI b5/b6, female gonopore in furrow of XIII a1/a2, gonopores separated by 6 annuli. Paired epididymides in XVI a2/b5-XVII b5 to XVI b5-XVII b6. Atrial cornua, coniform, undeveloped.

Material examined.

NSMT-An 53, holotype, dissected by Richardson, LR, collected from a home garden of Professor Masaharu Kawakatsu, Sapporo, Hokkaido, Japan, by Tetsuya Kawakatsu and Miyuki Kawakatsu on 1 June, 1974.

Additional materials. 22 specimens collected from Hokkaido, Japan. Six specimens collected from Maruyama–koen Park, Chuo–ku, Sapporo: KUZ Z24, dissected, and Z140 (43°03.12'N, 141°18.53'E; Alt. 50 m) by Naoyuki Nakahama on 14 June, 2009; KUZ Z166, Z167, dissected (43°03.15'N, 141°18.71'E; Alt. 34 m), Z168 and Z169, dissected (43°03.15'N, 141°18.61'E; Alt. 29m), by TN on 5 October, 2010. Six specimens from Sounkyo, Kamikawa: KUZ Z154, dissected, and Z155 (43°43.55'N, 142°57.53'E; Alt. 705 m), by Naoki Koike on 16 August, 2010; KUZ Z183 (43°43.45'N, 142°56.86'E; Alt. 674 m), Z184 and Z185 (43°43.39'N, 142°56.88'E; Alt. 678 m), and Z187 (43°43.29'N, 142°56.87'E; Alt. 758 m), by TN on 19 September, 2011. Two specimens from Mt. Asahidake, Higashikawa by Naoyuki Nakahama: KUZ Z141, dissected (43°38.82'N, 142°47.73'E; Alt. 1090 m) on 16 June, 2009, and KUZ Z142 (43°39.12'N, 142°48.10'E; Alt. 1120 m) on 17 June, 2009. Two specimens from near the Kabutonuma Pond, Toyotomi (45°13.22'N, 141°41.07'E; Alt. 16 m), by Naoki Koike on 6 August, 2010: KUZ Z147 and Z148, dissected. Two specimens from Mt. Rishirizan, Rishirifuji (Rishirito Island) (45°11.99'N, 141°14.26'E; Alt. 914 m), by Naoki Koike on 8 August, 2010: KUZ Z149 and Z150, dissected. KUZ Z143, dissected, from Nukabira, Kamishihoro (43°22.05'N, 143°11.62'E; Alt. 490 m), by Naoyuki Nakahama on 18 June, 2009. KUZ Z152, dissected, from Mt. Rausudake, Shari (44°06.09'N, 145°06.09'E; Alt. 630 m), by Naoki Koike on 13 August, 2010. KUZ Z153, dissected, from Mt. Meakandake, Ashoro (43°23.70'N, 143°59.23'E; Alt. 755 m), by Naoki Koike on 15 August, 2010. KUZ Z159, dissected, from near the Shinsennuma Pond, Kyowa (42°56.17'N, 140°35.57'E; Alt. 781 m), by Naoki Koike on 19 August, 2010.

Emended description.

Body firm, muscular, elongated, gaining regularly in width in caudal direction, dorso-ventral depressed, sides nearly parallel from mid length to point just anterior of caudal sucker (Figs 6, 7), maximu BL 111.64 (KUZ Z142), maximun BW 8.19 (KUZ Z154). Caudal sucker ventral, ova, its diameter smaller than BW (Figs 6, 7, 9D, 10D). In life, dorsal surface grayish blue, ventral surface bluish white (Fig. 8). Color faded in preservative, without any dark lines (Figs 6, 7).

Somite I completely merged with prostomium (Fig. 10A). Somite II uniannulate (Figs 9A, 10A). Somite III uniannulate in small specimens, biannulate in large specimens (Figs 9A, 10A). Somite IV generally biannulate (Figs 9A, 10A), but uniannulate in a few small specimens. Somite V biannulate, (a1 + a2) = a3, V a3 forming posterior margin of oral sucker (Figs 9 A–B, 10 A–B). Somites VI and VII triannulate, a1 = a2 = a3 (Figs 9 A–B, 10 A–B). Somites VIII–XXV quadrannulate, a1 = a2 = b5 = b6 (Figs 9 A–E, 10 A–E); X b5 being first annulus of clitellum, XIII a2 being last annulus of clitellum. Somite XXVI triannulate, a1 = a2 = a3, a3 being last complete annulus on venter (Figs 9 C–D, 10 C–D); a3 with furrow on dorsal in large specimens (Fig. 10C). Somite XXVII uniannulate, or biannulate; anus behind it with no post-anal annulus (Fig. 9C, 10C).

Anterior ganglionic mass in VI a2- VII a1. Ganglion VII in a2, a2 and a3, or a3. Ganglia VIII–XV mainly in a2 of each somite, but also a2 and b5, or b5 in several specimens (Fig. 11A). Ganglion XVI in a2 (Fig. 11A). Ganglia XVII–XXIV generally in a2 of each somite (Fig. 11A), but rarely in a1 and a2, or a2 and b5. Ganglion XXV generally in a1, but also a1 and a2, or a2 in several specimens. Ganglion XXVI in a1, XXV b6, XXV b6 and XXVI a1, or XXVI a2. Posterior ganglionic mass in XXVI a1-a3.

Eyes three pairs, first pair dorsally on posterior margin of II, second and third pairs dorsolaterally on posterior margin of V (a1 + a2) (Fig. 10A); eyes one pair in several large specimens, dorsally on posterior margin of II. Nephridiopores in 17 pairs, ventrally at posterior margin of a1 of each somite of VIII–XXIV (Fig. 10B, E); rarely in 18 pairs at a1 of each somite of VIII–XXV (NSMT-An 53, KUZ Z24, Z143, and Z155) (Fig. 9B, D–E). Papillae numerous, minute, hardly visible, one row on every annulus.

Pharynx agnathous, euthylaematous, reaching to XIV a2-XIV/XV (Fig. 10F). Crop tubular, acaecate, in XIVa2-XIV/XV to XX b5/b6-XXI a1/a2. Gastropore conspicuous, ventral, generally in furrow of XIII a1/a2 (Figs 9 E–F, 10E, G). Gastroporal duct, simple tubular, thin-walled, joining with crop in XIV a2-XIV/XV (Fig. 10F). Intestine tubular, acaecate, in XIV a2-XIV/XV to XXIII b5-XIV b5/b6. Rectum, tubular, thin-walled.

Male gonopore generally in furrow of XI b5/6, or at anterior part of XI b6 (Figs 9E, 10E). Female gonopore in furrow of XIII a1/a2, located behind gastropore (Figs 9F, 10G). Gonopores separated by six annuli (Figs 9E, 10E). Testisacs multiple, two or three testisacs on each side in each annulus, in XVI b5-XVII b6 to XXIII a1-XXV b6 (Fig. 11A). Paired epididymides in XVI a2/b5-XVII b5 to XVI b5-XVII b6 (Fig. 11A). Ejaculatory bulbs absent. Ejaculatory ducts in XI b5 to XVI a2/b5-XVII b5, loosely coiled, each winding from each junction with epididymis, narrowing at junction with atrial cornu, then turning inward toward atrial cornu without pre-atrial loop (Fig. 11 A–D). Pair of atrial cornua in XI b5 and b6, undeveloped, coniform (Fig. 11B). Atrium short, muscular, globular in XI b5 and b6 (Fig. 11 B–D). Ovisacs one pair, thin-walled, globular, in XIII a2 and b5 (Fig. 11A, E). Oviducts thin-walled, right or left oviduct crossing ventrally beneath nerve cord, both oviducts converging into common oviduct in XIII a2 (Fig. 11A, E). Common oviduct thin-walled, short, directly ascending to female gonopore (Fig. 11E).

Distribution.

Known in mountainous regions of Hokkaido, Japan (Fig. 1).

Remarks.

Richardson (1975) described that a gastropore of the holotype opened at the middle of XIII a1, and the female gonopore in the furrow of XIII a1/a2. However, both the gastropore and the female gonopore of Orobdella kawakatsuorum are in the furrow of XIII a1/a2 on the basis of examination of the holotype and newly collected specimens. A gastropore of this species is coincident with a female gonopore. Richardson also noted that a pair of nephririopores opened in XXV (XXIV in his paper). But it is rare for Orobdella kawakatsuorum to possess 18 pairs of nephridiopores.