Mimobdella japonica Blanchard, 1897

Nakano, Takafumi, 2011, Holotype redescription of Mimobdella japonica (Hirudinida, Arhynchobdellida, Erpobdelliformes) and taxonomic status of the genus Mimobdella, ZooKeys 119, pp. 1-10 : 3-5

Mimobdella japonica Blanchard, 1897 Figs 14

Mimobdella japonica Blanchard, 1897: 94-95, pl. 6, figs. 16, 17.

Diagnosis.

Mid-body somites novem-annulate, generally c1 = c2 <b2 <a2> c9 = c10 = d21 = d22 <c12. Anus at 172th (antepenultimate)/173th (penultimate) annuli with two post-anal annuli. Post-crop caeca in pairs in XXI c2-c10. Male gonopore at XI/ XII. Female gonopore at XII/XIII. Gonopores separated by 9 annuli (one full somite). Sperm duct reaching to XVI b1. Ovisacs reaching XXI a2.

Material examined.

RMNH.VER.650. Holotype, slightly contracted specimen, dissected, collected from Japan by P. F. von Siebold.

Description of holotype.

Body firm, muscular, gaining regularly in width in caudal direction, dorso-ventrally, depressed, BL 63.0 mm, BW 7.0 mm (Fig. 1). Caudal sucker, ventral, oval, its diameter equal to half of BW (Figs 1, 2D). Color in life unknown.

Annulation of somites I–VII undecidable, comprised of 17 annuli; 14th annulus with obvious furrow on dorsal, 17th annuli with obvious furrow on dorsal and slight furrow on ventral; 10th and 11th annuli united on venter, forming posterior margin of oral sucker (Fig. 2A, B). Somite VIII sexannulate, b1 (c1, c2 on dorsal)> b2 <a2 <b5 (c9, c10)> c11 (d21, d22)> c12; b2, b5 and c11 with obvious furrow on dorsal and slight furrow on ventral (Fig. 2A, B). Somite IX novem-annulate, c1 = c2 <b2 <a2> c9 = c10 = d21 = d22 <c12; furrows of c9/c10 and d21/d22 shallower than others. Somites X–XXIIII novem-annulate, generally c1 = c2 <b2 <a2> c9 = c10 = d21 = d22 <c12 (Fig. 2E); each of b2 of somites XVII–XXIII and a2 of somites XVIII–XXIII with slight furrow; c9 of X being first annulus of clitellum, a2 of XIII being last annulus of clitellum. Somite XXIV octannulate, c1=c2=b2<a2 (b3, b4 on dorsal)>c9=c10<c11 (d21, d22)>c12; a2 with slight furrow on dorsal, c11 with slight furrow (Fig. 2C, D). Annulation of somites XXV–XXVII undecidable, comprised of 8 (167 th– 174th) annuli, 167th annulus with slight furrow, 172th annulus being last complete annulus on venter (Fig. 2C, D); anus at 172th (antepenultimate)/173th (penultimate) annuli with two post-anal annuli (Fig. 2D).

Anterior ganglionic mass in 13th and 14th annuli. Ganglion VII in 17th annulus. Ganglion VIII in a2 and b5. Ganglia IX–XXIV in a2 of each somite (Fig. 3A). Ganglion XXVI in 169th annulus. Posterior ganglionic mass in 170 th– 172th a nnuli.

Eyes undetectable. Nephridiopores in 17 pairs in VIII–XXIV, located ventrally at middle of b2 of each somite (Fig. 2B, D, F). Papillae numerous, minute, hardly visible, one row on each annulus.

Pharynx strepsilaematous, reaching to XIV c10/d21, with three myognaths separated by triangular papragnaths (Fig. 4A); each myognath bearing two conic stylets arranged in tandem, parallel to body axis (Fig. 4A). Crop tubular, reaching to XXI a2; post-crop caeca thin-walled, in pairs in XXI c2-c10 (Fig. 4B). Intestine tubular, acaecate, reaching to XIII a2. Rectum tubular, thin-walled.

Male gonopore at XI/XII (Fig. 2F). Female gonopore at XII/XIII (Fig. 2F). Gonopores separated by 9 annuli (Fig. 2F). Testisacs multiple in XVI c2 to 169th annulus, several testisacs on each side in each annulus (Fig. 3A). Sperm ducts in XII c1 to XVI b1, coiled, narrowing at junction with atrial cornu, then turning gently inward toward atrial cornu without pre-atrial loop (Fig. 3A, D, E). Atrium short, muscular with atrial cornu in pairs in XI c12 and XII c1; atrial cornu, curved laterad (Fig. 3 B–E). Ovisacs long, slightly folded, tubular in XIII c1 to XXI a2; right ovisac turned anteriorly in XXI a2, reaching to XIX/XX; left ovisac also turned anteriorly in XXI a2, reaching to XIX b2; both ovisacs converged in XIII c1, directly descending to female gonopore (Fig. 3A).