Orobdella ganini Nakano & Prozorova 2024, sp. nov.
Creators: name: Nakano, Takafumi
name: Prozorova, Larisa A.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Clitellata
Arhynchobdellida
Orobdellidae
Orobdella
Orobdella ganini

description: Orobdella ganini sp. nov.
Figs 3–5
urn:lsid:zoobank.org:act: 183F362C-9006-4880-8FB8-286EB2797 CAD
Orobdella cf. tsushimensis — Prozorova (2019: 43–44, figs 1A, 2).
Orobdella sp. — Prozorova & Nakano (2020: 27, fig. 2).
Material examined. Holotype: Russia • Primorsky Krai, Lazovsky Nature Reserve, near Zvoyzdochka Cordon; 43.01739°N, 133.72946°E; 7 Aug. 2019; Dmitry Ionutsa leg.; KUZ Z5038. Paratypes: Russia • same data as for holotype; KUZ Z5042 – Z5044; same locality as for holotype; 7 Aug. 2019; Maxim Astakhov leg.; FSC (LAP8384); same locality as for holotype; 9 Oct. 2019; Larisa Prozorova leg.; FSC (LAP8498); near same locality as for holotype; 43.018056°N, 133.729444°E; June 2013; Gennady Ganin and P. Chukhmasov leg.; FSC (LAP9073). Additional material: Russia • Primorsky Krai, Lazovsky Nature Reserve, near America Cordon; 43.25547°N, 134.03746°E; 5 Aug. 2019; L. Prozorova leg.; KUZ Z5025. Four specimens, KUZ Z5025, Z5038, Z5043 and Z5044 were dissected.
Diagnosis. Body length of mature individuals reaching ~ 10 cm. Somite IV uniannulate, somites VIII–XXV quadrannulate; each of annuli of mid-body somites often with secondary furrow. Clitellum in somite XI b5 to somite XIII a2. Male gonopore in middle of XI b6, female gonopore in somite XIII a1/a2, gonopores separated by 1/2 + 5 annuli. Pharynx reaching to somite XIII b6–XIV a1/a2. Gastropore conspicuous, in somite XIII a1/a2. Gastroporal duct bulbous. Paired epididymides in somites XVI–XVIII, occupying eight or nine annuli. Atrial cornua developed, ovate.
Description of the holotype. Body firm and muscular, elongated, with constant width in posterior direction, dorsoventrally compressed; BL 88.8 mm, BW 6.2 mm (Fig. 3A, B). Caudal sucker ventral, elliptic, CL 3.1 mm, CW 3.6 mm (Figs 3B, 4C, D).
Somite I completely merged with prostomium (Fig. 4A). Somite II (= peristomium) uniannulate (Fig. 4A). Somites III–V biannulate, (a1 + a2) = a3 (Fig. 4A); a3 forming posterior margin of oral sucker (Fig. 4B). Somite VI and VII triannulate, a1 = a2 = a3 (Fig. 4A, B). Somites VIII–XXV quadrannulate (Fig. 4A–F); somites VIII–X, a1 = a2 = b5 = b6 (Fig. 4A, B, F); somites XI–XVI and XIX, a1 = a2 = b5 <b6 (with obvious secondary furrow, c11 = c12) (Fig. 4E, F); somites XVII and XVIII, a1 (b1 = b2)> a2 = b5 <b6 (c11 = c12); somites XX–XXIII, a1> a2 = b5 <b6, b6 with slight furrow; somites XXIV and XXV, a1> a2 = b5 = b6 (Fig. 4C, D). Somite XXVI triannulate, a1> a2 <a3; a3 being ventrally last complete annulus (Fig. 4C, D). Somite XXVII uniannulate, with slight lateral furrow left-dorsally (Fig. 4C). Anus on dorsal surface, posterior to somite XXVII; post-anal annulus absent (Fig. 4C). Somite X b5 and somite XIII a2, respectively, first and last annuli of clitellum (Fig. 4F).
Male gonopore in middle of XI b6 (Fig. 4F). Female gonopore in somite XIII a1/a2 (Fig. 4F), inconspicuous, located posterior to gastropore (Fig. 4G). Gonopores separated by 1/2 + 5 annuli (Fig. 4F).
Anterior ganglionic mass in somite VI a3 and VII a1. Ganglion VII in somite VII a2 and a3. Ganglia VIII and XIII, of each somite, in b5 (Fig. 5B). Ganglion IX in somite IX a2 and b5. Ganglia X–XII and XIV–XXV, of each somite, in a2 (Fig. 5B). Ganglion XXVI in somite XXVI a1. Posterior ganglionic mass in somite XXVI a2 and a3.
Eyespots in one pair on anterior margin of somite III, with one eyespot right-dorsolaterally on posterior margin of somite V (a1 + a2) (Fig. 4A). Papillae numerous, minute, hardly visible, one row on dorsal surface of every annulus.
Nephridiopores in 17 pairs, each situated ventrally at posterior margin of a1 of each somite from VIII to XXIV (Fig. 4B, D, F).
Pharynx agnathous, euthylaematous, reaching to somite XIV a1/a2 (Fig. 5A). Crop tubular, acecate, reaching to somite XX b5/b6. Intestine tubular, acecate, reaching to somite XXV a1. Rectum tubular, thin-walled, straight. Gastropore conspicuous, ventral, in somite XIII a1/a2 (Fig. 4F, G). Gastroporal duct bulbous, slightly winding at junction with gastropore, reaching to somite XIV a1/a2 and connecting with anteriormost part of crop (Fig. 5A).
Testisacs multiple (Fig. 5B); on right side, in total ~43 testisacs, in somite XVIII b5 to XXIII b5, 4 in XVIII, 8 in XIX, 6 in XX, 9 in XXI, 9 in XXII, 7 in XXIII; on left side, in total ~61 testisacs, in somite XVIII a2 to XXIV b6, 5 in XVIII, 8 in XIX, 8 in XX, 8 in XXI, 11 in XXII, 10 in XXIII, 11 in XXIV. Paired epididymides (Fig. 5B); right epididymis in somite XVI a2 to somite XVIII a1/a2, occupying eight annuli; left epididymis in somite XVI a2 to somite XVIII a2, occupying nine annuli. Paired ejaculatory ducts in somite XI b5 to somite XVI a2 (Fig. 5B); coiled in position posterior to ovisacs; each duct crossing ventrally beneath each ovisac, then nearly straight in position anterior to ovisacs; each winding from respective junction with epididymis, narrowing at junction with atrial cornua, then loosely turning proximally toward atrial cornua without pre-atrial loop. Pair of muscular atrial cornua developed, ovate, in somite XI b5 and b6 (Fig. 5B–E). Atrium short, muscular, globular in somite XI b5 and b6 (Fig. 5C–E).
Paired ovisacs globular, in somite XIII a2 and b5, right oviduct crossing ventrally beneath nerve cord; both oviducts converging into common oviduct in somite XIII a2/b5 (Fig. 5B, F). Common oviduct thin-walled, short, directly descending to female gonopore (Fig. 5B, F).
Variation. Measurements (mean ± 1SD, followed by ranges in parentheses; n = 5, including holotype): BL 78.7 ± 14.9 mm (56.0– 88.8 mm), BW 5.5 ± 1.1 mm (3.6–6.3 mm), CL 2.5 ± 0.6 mm (1.6–3.1 mm), CW 3.3 ± 0.5 mm (2.4–3.6 mm). Somite III uniannulate. Somite IV uniannulate with obvious secondary furrow dorsally. Somites XVI–XIII quadrannulate, a1 (b1 = b2)> a2 = b5 <b6 (c11 = c12), or a1 (b1 = b2)> a2 (b3 = b4 dorsally) = b5 <b6 (c11 = c12). Somite XXVII uni- or biannulate. Eyespots in three pairs, 1st pair dorsally on somite II/III, 2nd and 3rd pairs dorsolaterally on posterior margin of somite V (a1 + a2) (KUZ Z5025), or in one pair with two eyespots— one right-dorsolaterally and the other left-dorsolaterally—on posterior margin of somite V (a1 + a2) (KUZ Z5042, Z5043). Pharynx reaching to somite XIII b6–XIV a1/a2. Crop reaching to somite XX a2/b5–b5. Intestine reaching to somite XXIV b5–b6, with one pair of pouch-shaped intestinal ceca in somite XX a2–b6 (Fig. 5G). Gastroporal duct reaching to somite XIII b6–XIV a2/b5. Epididymides in somite XVI a2–b5/b6 to somite XVIII a1/a2–b5, occupying eight or nine annuli. Paired ejaculatory ducts in somite XI b5 to somite XVI a2–b5/b6; loosely coiled or straight in position anterior to ovisacs. Paired ovisacs in somite XIII a2. Right or left oviduct crossing ventrally beneath nerve cord; both oviducts converging into common oviduct in somite XIII a2.
Coloration. In life, dorsal surface reddish brown (Fig. 3C); ventral surface whitish orange; clitellum, when obvious, paler than other body parts (Fig. 3C). Color faded in preservative.
Etymology. The specific name is formed directly from the name of the late Dr. Gennadiy Nikolaevich Ganin, a famous Russian specialist in soil invertebrates. He provided the first record of a large Orobdella from the LNR in the Zvoyzdochka Cordon area and donated an ethanol preserved specimen to L. Prozorova. This specimen was studied morphologically and tentatively identified as new to science (Prozorova 2019; Prozorova & Nakano 2020). Later, thanks to correct GPS data provided by the late Dr. Ganin, we found leeches in the same locality near the Zvoyzdochka Cordon and then collected other specimens of the new Orobdella species living in sympatry with O. ghilarovi near the America Cordon.
Distribution and natural history. We collected this species only in the LNR. The individuals were found curled up under rocks or fallen leaves in the forest during the daytime. Because a mature individual (= holotype) bearing a clitellum and developed testisacs and ovisacs was collected on 7 August 2019, we estimate that the reproductive season of this species is around August. It is noteworthy, however, that the other large individuals we collected did not bear either a clitellum or detectable testisacs.
Remarks. Orobdella ganini sp. nov. unquestionably belongs to the genus Orobdella by its possession of the diagnostic features of the genus (see Nakano 2016), and its molecular phylogenetic position.
Orobdella ganini sp. nov. differs from the 14 quadrannulate congeners in the following combination of characteristics (see also Nakano 2021; Table 3): middle-type body length, uniannulate somite IV, mid-body somite annuli each with a secondary furrow, quadrannulate somite XXV, 1/2 + 5 annuli between gonopores, pharynx reaching to anterior of somite XIV, bulbous gastroporal duct, epididymides in somites XVI–XVIII that occupy eight or nine annuli, and developed ovate atrial cornua. The new species is unquestionably distinguishable from the seven sexannulate species and two octannulate species by its quadrannulate mid-body somites.
description: Published as part of Nakano, Takafumi & Prozorova, Larisa A., 2024, Terrestrial predatory leeches of the genus Orobdella (Hirudinea: Erpobdelliformes: Orobdellidae) endemic to the Southern Russian Far East: a new species of the genus from Primorsky Krai, Russia, pp. 44-60 in Zootaxa 5424 (1) on pages 50-55, DOI: 10.11646/zootaxa.5424.1.2, http://zenodo.org/record/10807975