Odontobdella gaowangjiensis Yin & Liu, 2025

Yin, Zihan, Liao, Jinping, Li, Linbei, Xiang, Haiyang, Xiang, Dongqin, Liu, Zhixiao & Nakano, Takafumi, 2025, A new species of Odontobdella Oka, 1923 (Erpobdelliformes: Salifidae), a macrophagous terrestrial leech from Central China, Zootaxa 5566 (1), pp. 159-172 : 163-165

Odontobdella gaowangjiensis Yin & Liu , sp. nov.

Figs 1a , 2–3

Materials examined. Holotype. HNGWJ01 ; adult; body length 170.79 mm, maximal body width 9.63 mm, width of anterior sucker 6.08 mm, width of posterior sucker 8.34 mm; Gaowangjie National Nature Reserve , Guzhang County, Xiangxi Prefecture, Hunan Province, China; 28.6588°N, 110.0849°E, 900 masl; collected by Zihan Yin, 24 May 2023 ( Figs 2–3 ) . Paratypes. Seven specimens HNGWJ02 – HNGWJ08 ; Gaowangjie National Nature Reserve , Guzhang County, Xiangxi Prefecture, Hunan Province, China .

Diagnosis. Mid-body somites decem-annulate, in adult worms, c1 = c2 = c3 = c4 <b3 = b4 <c9 = c10> c11 = c12; in juveniles, quinquannulate, b1 = b2 = a2 <b5 (c9 = c10)> b6. Post-anal annuli present. Eyespots in six pairs, on somites II, III, IV and V; second pair on somite II largest. Each of three myognaths bearing two conical stylets arranged in tandem, parallel to body axis. Male gonopore in somite XI c11/c12 (slightly posterior to middle of somite XI b6), female gonopore in somite XII c11/c12 (slightly posterior to middle of somite XII b6), gonopores separated by ten annuli (= one full somite). Atrial cornua heart-shaped, curved laterad. Ovisacs tubular, extending to somite XVII.

Description. Body muscular, oblate columnar, behind gonoporal region with constant width in caudal direction; from head to female gonopore cylindrical; behind female gonopore slightly raised dorsal, ventral surface relatively flat; body length approx. 200 mm in adults, approx. 50 mm in juveniles, in holotype, body length 170.79 mm, maximum body width 9.63 mm, head width 5.89 mm. Caudal sucker ventral, disc-shaped, length (from anterior margin to posterior margin) 9.24 mm, width (from right margin to left margin) 8.34 mm. When living, the dorsum is black, the ventrum is dark brown. The body appears grayish white, without any spots and markings in preservative.

Somite I completely merged with prostomium. Somites II (= peristomium) and III uniannulate. Somites IV and V biannulate. Annulation of somites VI–VIII unclear, comprising 14 annuli altogether. According to annuli formation, annulation of somites VI–VIII tentatively interpreted as follows: somite VI quadrannulate, a1 = a2> b5 = b6; somites VII and VIII quinquannulate, b1 = b2 = a2 <b5> b6. Somites IX–XXIV decem-annulate, c1 = c2 = c3 = c4 <b3 = b4 <c9 = c10> c11 = c12; in juveniles, quinquannulate, b1 = b2 <a2> b5 (c9 = c10)> b6, b5 with secondary furrow. Somite XXV quadrannulate, b1 = b2 <a2 = a3. Somite XXVI triannulate. Somite XXVII biannulate. Anus at XXVI a1/a2 with four post-anal annuli. Somite X c9 and somite XII b3 (= anterior part of a2), respectively, first and last annuli of clitellum.

Male gonopore in somite XI c11/c12 (= slightly posterior to middle of somite XI b6). Female gonopore in somite XII c11/c12 (slightly posterior to middle of somite XI b6). Gonopores separated by ten annuli (= one full somite).

Eyespots in six pairs, in parabolic arc, second pair largest; first and second pairs on somite II, third pair on somite III, fourth pair on somite IV, fifth and sixth pairs on somite V (a1 + a2); one eyespot occasionally undetectable in each of the third and fourth pairs. Papillae numerous, minute, one transversal row dorsally on every annulus.

Pharynx strepsilaematous, with three myognaths separated by triangular paragnaths, each myognath bearing two conical stylets arranged longitudinally in tandem, parallel to body axis.

Testisacs undeveloped, and thus undetectable on both sides. Paired sperm ducts in posterior of somite XI to somite XVII, coiled, narrowing at junction with atrial cornua, then turning inwards towards atrial cornua without pre-atrial loop. Pair of atrial cornua large, heart-shaped, curved laterad. One pair of ovisacs long, tubular, uncoiled, in somite XIII to somite XIV; both ovisacs directly descending to female gonopore. In some individuals, sperm ducts intertwined with ovisacs, and then both curved.

Etymology. The specific name gaowangjiensis refers to the type locality, Hunan Gaowangjie National Nature Reserve, Central China.

Geographical distribution. Gaowangjie Forest Farm, Gaofeng Township, Guzhang County, Xiangxi Tujia and Miao Autonomous Prefecture, Hunan Province, China.

Ecology. Sometimes seen on rainy days and at night, usually in a contracted, dorsally curved shape; dead or near-dead individuals occasionally seen lying beside roads, or in puddles after rain.

Remarks. We concluded that the new species belongs to the genus Odontobdella , because it bears the following morphological features, which have been considered the diagnostic characters of the genus ( Sawyer 1986; Nesemann & Sharma 2012; see also Nakano & Nguyen 2015): its female gonopore opens in the posterior part of somite XII; its elaborate mid-body somite annulation, i.e., each somite consists of more than nine unequal annuli; the styles that are parallel to the body axis; and the absence of accessory copulatory pores. Four species of this genus have been described: O. blanchardi ( Oka, 1910) , O. quadrioculata Oka, 1922 , O. polaneci Nesemann, 1995 , and O. krishna Nesemann & Sharma, 2012 ( Nakano & Nguyen 2015). In addition to the species of Odontobdella , the morphological features of O. gaowanghiensis sp. nov. resemble those of the salifid M. japonica Blanchard, 1897a and S. kinzelbachi ( Nesemann, 1995) , endemic to East Asia. However, O. gaowangjiensis sp. nov. can be distinguished from those species by the following combination of characteristics ( Oka 1923; Nesemann 1995; Nakano 2011, 2013; Nesemann & Sharma 2012; Nakano & Nguyen 2015): male gonopore in somite XI c11/c12 (= slightly posterior to middle of somite XI b6) (in somite XI/XII in O. blanchardi and M. japonica ; in middle of somite XII b 1 in O. krishna and O. polaneci ; in XI c 12 in O. quadrioculata ); female gonopore in somite XII c11/c12 (= slightly posterior to middle of somite XII b6) (in somite XII b5/b6 or in middle of somite XII b 6 in O. blanchardi ; in somite XII c10/d 21 in O. quadrioculata ; in somite XII/somite XIII in M. japonica ); and stylets that are parallel to the body axis (transverse to the body axis in S. kinzelbachi ). Salifid leeches from China, which were identified as O. blanchardi , were described as possessing four or five pairs of eyespots ( Yang 1997). The second pair of eyespots of O. gaowangjiensis sp. nov. may correspond to the first pair of eyespots of the Chinese O. blanchardi , and thus, the new species can also differ from the latter by the number of eyespots.

Figures

FIGURE 1. Geographical locality of the sampling site of leech specimens used in this study. A. Overview of China’s provinces. B. General map of Xiangxi Prefecture. C. Landscape of specimen collection site. a. Dorsal view of Odontobdella gaowangjiensis sp. nov.

FIGURE 2. Morphological characteristics of Odontobdella gaowangjiensis sp. nov. A. Ventral view of the holotype specimen. B. Dorsal view of the holotype (note that the specimen was preserved in 75% alcohol before being photographed). Dorsal (C), and ventral (D) views of somites XI–XII. Dorsal (E), and ventral (F) views of somites I–VIII. Dorsal (G), and ventral (H) views of somites XXIV–XXVII and caudal sucker. Abbreviations: fg—female gonopore; mg—male gonopore. Scale bars: 1 cm (A, B), 5 mm (C–H).

FIGURE 3. Reproductive system, pharyngeal anatomy and eyespots distribution of Odontobdella gaowangjiensis sp. nov. A. Distribution of eyespots. B. Pharyngeal anatomy. C. Anatomical morphology of female and male reproductive systems. Abbreviations: ac—atrial cornua; at—atrium; gang—ganglion; ov—ovisac; ovd—oviduct; pr—pharynx ridge; sd—sperm ducts; spd—spermaduct; st—stylets; mg, male gonopore; fg, female gonopore; 2nd PE, second pair of eyes; 6th PE, sixth pair of eyes.