Paraclepsis Harding, 1924

Genus Paraclepsis Harding, 1924 gen. rev.

Figure S2

Type species. Paraclepsis praedatrix Harding, 1924 (subsequent designation by Soós, 1969).

Differential diagnosis. Small leeches (length up to 15.5 mm; Harding 1924); three pairs of eyespots on III, IV a1 and V a2 (second and third pairs of eyespots are separated by two annuli); body with 70-73 annuli, mid-body somites triannulate; dorsum with four rows of ovate shallow papillae; mouth pore is subterminal (near the rim of the anterior sucker); two pairs of compact salivary glands; esophagus with broad, bag-like pharingeal bulb; seven pairs of crop caeca; six pairs of testisacs; gonopores separated by two annuli: male gonopore on XI a3 / XII a1, female gonopore on XII a2 / XII a3; posterior sucker is small, circular, ventrally directed. Phylogenetically, this genus represents a separate, distant group that is sister to the clade Orientobdelloides + Batracobdella .

Distribution. India, Sri Lanka, Thailand, Vietnam, and South-East China ( Table 3).

List of species. Paraclepsis cancricola ( Oka, 1928) [South-East China]; Pa. dongnaiensis sp. nov. [ Thailand and Vietnam]; Pa. ceylanica ( Harding, 1909) [= Pa. vulnifera Harding, 1924 syn. nov.; = Pa. praedatrix Harding, 1924 syn. nov.; India and Sri Lanka] ( Table 3).

Hosts. Historically, freshwater turtles ( Trionychidae ) and crabs ( Gecarcinucidae ) were considered hosts for leeches in this genus ( Harding 1924; Harding and Moore 1927; Soós 1969). However, there are reliable records from frogs ( Dicroglossidae ) ( Kaburaki 1921; Chandra and Mukharjee 1973) and from the buccal cavity of an aquatic snake ( Colubridae ) ( Chandra and Saha 1967). In our opinion, relationships of these leeches with turtles and crabs may be regarded as phoretic/dwelling biotic interactions, whereas frogs and the snake may serve as primary hosts ( Table 3). It is well known that various leech species (both parasitic and predatory taxa) may use turtles as phoretic hosts (e.g., Oosthuizen 1991; Marrone et al. 2016; Perera et al. 2019; Watermolen 2021).

Comments. Our concept of Paraclepsis is largely based on the morphology-based revision of Sawyer (1986), who transferred the nominal taxa Placobdella ceylanica and Batracobdella cancricola to this genus. This author also assumed that Paraclepsis vulnifera may represent an intraspecific form of Pa. praedatrix but did not formally synonymize these nominal species ( Sawyer 1986: 764).

Three nominal species from India and Sri Lanka, that is, Paraclepsis ceylanica , Pa. vulnifera , and Pa. praedatrix cannot be delineated using the morphological and anatomical diagnostic characters presented in their original descriptions and subsequent re-descriptions ( Figure S2; Harding 1909; Kaburaki 1921; Harding 1924; Harding and Moore 1927). For instance, Pa. vulnifera is similar to Pa. praedatrix but differs from it by a few minor traits as follows: (1) the head region is continuous with the body and is not separated from it by a posterior constriction; (2) smaller number of annuli (70 vs. 73); and (3) the lack of large vesiculae seminales ( Harding 1924; Harding and Moore 1927). It was also noted that the condition of the type series of Pa. vulnifera was unfavorable for observation of the papillae and coloration ( Harding 1924). In our opinion, the shape of the head region cannot be used as a reliable diagnostic trait in leeches because this feature may vary depending on the condition of specimens and the methods of their fixation (see the series of specimens on Figure 8 A-F). The precise counting of the total number of annuli can be difficult in contracted specimens, while the development of vesiculae seminales may differ depending on the degree of maturity of individuals. Therefore, we agree with Sawyer’s (1986) assumption that the two nominal species are conspecific. Moreover, they are morphologically indistinguishable from an older nominal species, Paraclepsis ceylanica , and are considered its synonyms.

Here, we also confirm the placement of Paraclepsis cancricola , a crab-associated leech from South-East China, in this genus based on the phylogenetic evidence (see Figure 7). Morphologically, this leech fully aligns with the generic diagnosis and has three pairs of eyespots with the two posterior pairs separated by two annuli, body with 70 annuli, seven pairs of crop caeca, esophagus with an esophagial bulb, six pairs of testisacs, and two annuli between gonopores ( Yang 1986).

Two nominal species in the genus Paraclepsis were recently described from India:

(1) Paraclepsis gardensi Mandal, 2004 [holotype: ZSI An 2768/1; type locality: King Lake, 22.5598°N, 88.2879°E, Botanical Garden, Shibpur, Howrah, West Bengal, India; host: unknown] ( Mandal 2004);

(2) Paraclepsis jorapariensis Mandal, 2015 [holotype: ZSI An 3702/1; type locality: Jorapari, 24.1°N, 86.3°E, Giridih District, Jharkhand, India; host: unknown] ( Mandal 2015).

Although the DNA sequences of these nominal species are not available, they cannot be considered representatives of the original genus based on morphological criteria. In particular, Paraclepsis gardensi is characterized by (1) three pairs of eyespots with the two posterior pairs separated by one annulus, and (2) the position of the mouth pore in the anterior half of the oral sucker ( Figure S3). There is a peculiar subgroup in the genus Hemiclepsis Vejdovsky, 1884 , the representatives of which have three pairs of eyespots in this kind of arrangement, as well as a similar position of the mouth pore. This subgroup contains three species: Hemiclepsis bhatiai Baugh, 1960 [Bihar and Jammu and Kashmir, India], Hm. erhaiensis Yang, 1981 [Erhai, Dianchi and Chenghai lakes, Yunnan, China], and Hm. viridis Chelladurai, 1934 [Kerala and Tamil Nadu, India] ( Chelladurai 1934; Baugh, 1960a; Yang 1996; Bolotov et al. 2019). The second pair of eyespots is the largest in Hemiclepsis bhatiai and Paraclepsis gardensi . However, the latter species can be distinguished from Hemiclepsis bhatiai by having 18 longitudinal greenish stripes on the dorsum (vs. four longitudinal series of brown spots). In turn, dorsum of Hemiclepsis viridis bears 15 to 25 longitudinal green lines but in this nominal species the third pair of eyespots is the largest ( Chelladurai 1934). It is known that the size of eyespots in the Glossiphoniidae is rather variable ( Soós 1969; but see Eliseeva et al. 2024 for exception). Moreover, a paratype of Paraclepsis gardensi has the second and third pair of eyespots of similar size ( Figure S3). Therefore, we propose the new synonymy as follows: Hemiclepsis viridis Chelladurai, 1934 [= Paraclepsis gardensi Mandal, 2004 syn. nov.].

Paraclepsis jorapariensis Mandal, 2015 was described based on a single specimen (the holotype). The original diagnosis of this species is as follows: length 15 mm; four pairs of eyespots: the first three pairs are in two subparallel rows, while the fourth pair is laterally arranged; dorsum with seven longitudinal greyish-yellow lines; four series of dorsal papillae; 71 annuli; the gonopores are separated by 2-3 annuli; and eight pairs of crop caeca ( Mandal 2015). The four pairs of eyespots rarely occur in the Glossiphoniidae View in CoL , being the diagnostic trait of only two genera: Theromyzon Philippi, 1867 View in CoL and Oosthuizobdella Sawyer, 1986 ( Sawyer 1986; Bolotov et al. 2022a). Theromyzon View in CoL has four pairs of eyespots in two subparallel rows, whereas Oosthuizobdella is characterized by the lateral position of the fourth (buccal) pair of eyespots ( Sawyer 1986; Nesemann et al. 2007). Based on this diagnostic feature, we consider that Paraclepsis jorapariensis belongs to the latter genus. Morphologically, the holotype of Paraclepsis jorapariensis largely agrees with Oosthuizobdella garoui (Harding, 1932) by having light greenish ground color of the body, dorsum with broken longitudinal brownish stripes, dark yellow spots at a 2 in outer paramedian, outer paramarginal and marginal positions ( Oosthuizen 1982; Nesemann et al. 2007; Mandal 2015: plate I). It seems to be an immature specimen of the same species. Therefore, we propose the new synonymy as follows: Oosthuizobdella garoui (Harding, 1932) [= Paraclepsis jorapariensis Mandal, 2015 syn. nov.].