Orobdella yamaneae, Nakano, Takafumi, 2016

Nakano, Takafumi, 2016, Four new species of the genus Orobdella from Shikoku and Awajishima island, Japan (Hirudinida, Arhynchobdellida, Orobdellidae), Zoosystematics and Evolution 91 (1), pp. 79-102 : 86-89

Taxon classification Animalia Arhynchobdellida Orobdellidae

Orobdella yamaneae sp. n. Figs 14, 15, 16, 17, 18

Type materials.

Holotype: KUZ Z1678, dissected, collected from under fallen leaves along a forest road, "Yuzuruha Forest Road" (34.24741°N, 134.80791°E; Elev. ca. 195 m; locality #1, see Fig. 1), at Mt. Yuzuruhasan, Awajishima island, Japan, by Yoshiko Yamane on 8 July 2015. Paratypes: six specimens collected from the type locality; KUZ Z1358 (34.245889°N, 134.811861°E; Elev. ca. 210 m), and Z1359 (34.246000°N, 134.812000°E; Elev. ca. 210 m), from under a rock along the forest road, by TN on 17 June 2011; KUZ Z1675-Z1677 (34.24743°N, 134.80777°E; Elev. ca. 195 m), and Z1679 (34.24711°N, 134.80884°E; Elev. ca. 195 m), from under fallen leaves along a forest road, by Yoshiko Yamane on 8 July 2015; three specimens, KUZ Z1358, Z1676 and Z1679, dissected.

Additional material.

KUZ Z1488, collected from under fallen leaves along the forest road (34.247222°N, 134.808611°E; Elev. ca. 215 m) at the type locality, by Yoshiko Yamane on 20 August 2013.

Type locality.

Japan, Hyogo Prefecture: Minamiawaji, Mt. Yuzuruhasan (Awajishima island).

Diagnosis.

Dorsal surface purplish. Somite VII quinquannulate. Somite VIII–XXVI sexannulate, b1 = b2 = a2 = c9 = c10 = b6. Male gonopore in middle of XI b6, female gonopore in slightly posterior to middle of XIII b 2, behind gastropore, gonopores separated by 1/2 + 7 + 1/2 annuli. Pharynx reaching to XIV a2/c9-c9. Gastropore conspicuous, in slightly posterior to middle of XIII b2. Gastroporal duct bulbous, slightly winding at junction with gastropore. Paired epididymides in XVI to XVIII, occupying 8-11 annuli (one and half to almost two somites). Pre-atrial loop present. Atrial cornua ovate.

Description of holotype.

BL 142.2 mm, BW 8.1 mm (Fig. 14). Caudal sucker ventral, elliptic, CL 3.0 mm, CW 5.1 mm (Figs 14B, 15D).

Somites III–V biannulate; III and IV, (a1 + a2)> a3; V, (a1 + a2) = a3; V a3 forming posterior margin of oral sucker (Fig. 15A, B). Somite VI triannulate, a1 (dorsally b1 = b2)> a2> a3 (Fig. 15A, B). Somite VII quinquannulate, a1 = a2 = c9 = c10 = b6 (Fig. 15A, B). Somites VIII–XXV sexannulate, b1 = b2 = a2 = c9 = c10 = b6 (Fig. 15 A–E). Somite XXVI sexannulate dorsally, b1 = b2 = a2> c9 = c10 = b6, quinquannulate ventrally, b1 = b2 = a2 <b5 (c9 = c10)> b6 (Fig. 15C, D). Somite XXVII comprises two annuli, first annulus with slight dorsal furrow; first annulus being ventrally last complete annulus (Fig. 15C, D). Anus behind somite XXVII (Fig. 15C).

X c9 and XIII a2, respectively, being first and last annuli of clitellum (Fig. 15E).

Male gonopore in middle of XI b6 (Fig. 15E). Female gonopore in slightly posterior to middle of XIII b2, inconspicuous, located posterior to gastropore (Fig. 15E, F). Gonopores separated by 1/2 + 7 + 1/2 annuli (Fig. 15E).

Anterior ganglionic mass in VI a2 and a3. Ganglion VII in a2. Ganglia VIII and IX, of each somite, in b2 and a2. Ganglia X–XII, of each somite, in a2 (Fig. 16A). Ganglion XIII in a2 and c9 (Fig. 16A). Ganglia XIV–XVIII, of each somite, in a2 (Fig. 16A). Ganglion XIX in b2 and a2. Ganglia XX–XXIV, of each somite, in a2. Ganglion XXV in b2 and a2. Ganglion XXVI in b1 and b2. Posterior ganglionic mass in XXVI c9-b6.

Eyes in three pairs, first pair dorsally on II/III, second and third pairs dorsolaterally on posterior margin of V (a1 + a2) (Fig. 15A).

Nephridiopores in 17 pairs, one each situated ventrally at posterior margin of b2 of each somite in VIII–XXIV (Fig. 15B, D, E).

Pharynx reaching to XIV a2/c9 (Fig. 15G). Crop reaching to XXI b6. Gastropore conspicuous, ventral, in slightly posterior to middle of XIII b2 (Fig. 15E, F). Gastroporal duct bulbous, slightly winding at junction with gastropore, joining with crop in XIV a2/c9 (Fig. 15G). Intestine reaching to XXIV c9/c10.

Testisacs in XVIII c9 to XXVI b1 (Fig. 16A): on right side, in total approx. 107 testisacs, 7 in XVIII, 13 in XIX, 16 in XX, 17 in XXI, 14 in XXII, 14 in XXIII, 14 in XXIV, 11 in XXV, 1 in XXVI; on left side, in total approx. 108 testisacs, 5 in XVIII, 12 in XIX, 19 in XX, 15 in XXI, 15 in XXII, 13 in XXIII, 14 in XXIV, 14 in XXV, 1 in XXVI. Paired epididymides; right epididymis in XVI c9 to XVIII c9, occupying 13 annuli; left epididymis in XVI c9/c10 to XVIII c9, occupying 12 annuli (Fig. 16A). Paired ejaculatory ducts; right duct in XI c9 to XVI c9; left duct in XI c9 to XVI c9/c10; coiled in position posterior to ovisacs; each duct crossing ventrally beneath each ovisac, then curved in position anterior to ovisacs; each widening from respective junction with epididymis, narrowing at junction with atrial cornua, then turning sharply inward toward atrial cornua with atrial loop extending to anterior of XI c9 (Fig. 16 A–D). Pair of muscular atrial cornua ovate, in XI c9-b6 (Fig. 16 A–D). Atrium short, muscular, globular in XI c10 and b6 (Fig. 16 A–D).

Paired ovisacs in XIII a2 and c9 (Fig. 16A, E). Oviducts; left oviduct crossing ventrally beneath nerve cord; both oviducts converging into common oviduct in XIII a2 (Fig. 16A, E). Common oviduct directly descending to female gonopore (Fig. 16A, E).

Variations.

BL 62.4-97.6 mm, BW 4.0-6.5 mm, CL 1.6-2.8 mm, CW 2.5-3.6 mm. Somite III uniannulate with slight dorsal furrow, [(a1 + a2)> a3]. Somite IV uniannulate with slight dorsal furrow, [(a1 + a2)> a3] in KUZ Z1359 (Fig. 17A). Somite VII quadrannulate in KUZ Z1359, a1 = a2 <b5 (ventrally c9 = c10)> b6 (Fig. 17A, B). Somite VIII quinquannulate in KUZ Z1359, b1 = b2 = a2 <b5 (c9 = c10)> b6 (Fig. 17A, B). Somite XXVI generally sexannulate, b1 = b2 = a2 = c9 = c10 = b6, or b1 = b2 = a2 = c9> c10 = b6; KUZ Z1359, quinquannulate, b1 = b2 = a2 <b5> b6. Somite XXVII comprises 2-4 annuli. XXVI b6, or first annulus of XXVII being ventrally last complete annulus. Female gonopore rarely in posterior margin of XIII b2, gonopores thus rarely separated by 1/2 + 8 annuli. First pair of eyes generally dorsally on posterior margin of II. Pharynx reaching to XIV a2/c9-c9. Crop reaching to XXI c9-XXII c9/c10. Gastroporal duct often tubular, slightly bulbous at junction with gastropore, joining with crop in XIV b1/b2-b2/a2. Intestine reaching to XXIV/ XXV–XXV a2/c9. Testisacs hardly detected. Paired epididymides: right epididymis in XVI b2-b2/a2 to XVII c9-XVIII b1, occupying 8-11 annuli; left epididymis in XIV b1/b2-XVI b2/a2 to XVII c9-XVIII b1, occupying 9-11 annuli. Paired ejaculatory ducts running straight, or nearly straight in position anterior to ovisacs; pre-atrial loop reaching to XI a2/c9-c9. Pair of muscular atrial cornua fusiform or ellipsoid, often in XI c10 and b6. Paired ovisacs generally in XIII a2 and c9; KUZ Z1358, in XIII c9. Right or left oviduct crossing ventrally beneath nerve cord.

Colouration.

In life, dorsal surface grayish purple or red-purple (Fig. 18); ventral surface whitish blue or grayish purple; clitellum, when obvious, paler than other body parts (Fig. 18). Color faded in preservative.

Etymology.

The specific name is a noun in the genitive case formed directly from the name of Ms Yoshiko Yamane, who collected specimens of this new species.

Distribution.

This species was collected only from its type locality.

Natural history.

This species was found curled up under fallen leaves in moist mountainous habitats. A mature leech, KUZ Z1678, was collected on 8 July. Therefore, Orobdella yamaneae is considered to enter its reproductive season before early July.

Remarks.

The mid-body somite annulation of the known sexannulate Orobdella species was described as being composed of b1, b2, a2, b5, c11 and c12 ( Nakano 2011b, 2012a). However, the annulation of somites VII [a1 = a2 <b5 (ventrally c9 = c10)> b6] and VIII [b1 = b2 = a2 <b5 (c9 = c10)> b6] of one specimen, KUZ Z1359, clearly suggests that b5 is divided into c9 and c10, and b6 remains undivided in Orobdella yamaneae . The sexannulation of this species is thus b1 = b2 = a2 = c9 = c10 = b6.

In addition to its unique sexannulation, Orobdella yamaneae is distinguishable from the four known sexannulate species and Orobdella okanoi by the following characteristics (Table 4): dorsal surface purplish, somite VII quinquannulate, somite VIII sexannulate, 1/2 + 7 + 1/2 annuli between gonopores, pharynx reaching to XIV, gastroporal duct bulbous, epididymides in XVI to XVIII, pre-atrial loop present and atrial cornua ovate. Orobdella yamaneae obviously differs from quadrannulate and octannulate species of this genus in its mid-body somite annulation.

Except for the holotype, all dissected individuals possess the following characteristics of the male genital or gan: ejaculatory ducts in position anterior to ovisacs running straight and male atrial cornua ellipsoid or fusiform. However, they seem to be immature leeches because all of them have undeveloped and undetectable testisacs. Therefore, straight ejaculatory ducts and ellipsoid or fusiform testisacs are considered to be immature characteristics of Orobdella yamaneae .