Batracobdelloides Oosthuizen, 1986

Genus Batracobdelloides Oosthuizen, 1986 gen. rev.

Figure S4

Type species. Helobdella tricarinata Blanchard, 1897 (by original designation).

Differential diagnosis. Small to medium-sized leeches (length up to 20 mm; Oosthuizen 1989); two pairs of eyespots on III (eyespots of the first pair are strongly reduced and usually joined with the second pair; eyespots of the second pair are larger, round or angulate, merging); body with 68-70 annuli, mid-body somites triannulate; dorsum with three or five longitudinal rows of prominent tubercles; mouth pore is shifted to the anterior part of the anterior sucker; salivary glands diffuse, extensively developed; proboscis slender; esophagus long, slender, slightly muscular; esophageal organ present; seven weakly branched pairs of crop caeca; gonopores separated by two annuli: male gonopore on furrow XI a3 / XII a1 and female gonopore on furrow XII a2 / XII a3; six pairs of testisacs; eggs carried in temporary, ventral brood chamber but not attached to the body; posterior sucker is small, circular, ventrally directed.

Distribution. Africa, South Asia ( India and Sri Lanka), South-East Asia ( Myanmar, Thailand, and Vietnam), East Asia ( South Korea), and the Greater Sunda Islands (Java, Indonesia). The former representative of this genus from Europe was recently transferred to its own monotypic genus: Eurobdelloides moogi (Nesemann & Csányi, 1995) ( Bolotov and Pešić 2025) . The latter taxon is a relict phylogenetic lineage and does not relate to the Batracobdelloides clade but has some degree of convergent morphological similarity with it.

List of species. The genus contains 12 accepted species: Batracobdelloides amnicolus (Moore, 1958) [ Republic of South Africa, Namibia, Lesotho, and Botswana]; B. bangkhenensis Chiangkul et al., 2021 [ Thailand]; B. conchophylus Bolotov et al., 2019 [ Myanmar]; B. fulvus ( Harding, 1924) comb. nov. [ India]; B. gracilis ( Blanchard, 1897) comb. nov. [Java, Indonesia]; B. hlaingbweensis Bolotov et al., 2019 [ Myanmar]; B. indochinensis Bolotov et al., 2019 [ Myanmar]; B. koreanus Bolotov et al., 2019 [ South Korea]; B. reticulatus ( Kaburaki, 1921) [ India]; B. tricarinatus ( Blanchard, 1897) [ Tanzania, Kenya, Uganda, Democratic Republic of the Congo, Angola, Sudan, Ghana, Zambia, Egypt, and, probably, Israel]; B. undulatus ( Harding, 1924) comb. nov. [ Sri Lanka, and, probably, India]; B. yaukthwa Bolotov et al., 2019 [ Myanmar] ( Oosthuizen 1989; Bolotov et al. 2019; Chiangkul et al. 2021b). Additionally, our samples contain three new mussel-associated Batracobdelloides species from South-East Asia (see Figure 7 and Table S1) that will be described elsewhere.

Hosts. Typically, freshwater molluscs act as shelter/dwelling place and/or secondary host and freshwater fishes serve as primary host ( Bolotov et al. 2019; Chiangkul et al. 2021b). However, available observations indicate that freshwater crabs may act as phoretic/dwelling host for two species ( Table 3).

Comments. Here, we transfer three nominal species from other genera to Batracobdelloides based on morphological features and propose new combinations as follows:

(1) Batracobdelloides fulvus ( Harding, 1924) comb. nov. [= Placobdella fulva Harding, 1924 ; = Placobdelloides fulva ( Harding, 1924) ; type locality: Purulia, 23.33°N, 86.36°E, West Bengal, India; phoretic/dwelling host: freshwater crab Maydelliathelphusa lugubris (Wood-Mason, 1871) ( Gecarcinucidae ); primary host: unknown (most likely fish)] ( Harding 1924; Soós 1969; Sawyer 1986);

(2) Batracobdelloides gracilis ( Blanchard, 1897) comb. nov. [= Helobdella gracilis Blanchard, 1897 ; = Placobdella gracilis ( Blanchard, 1897) ; = Batracobdella gracilis ( Blanchard, 1897) ; type locality: Bogor, 6.60°S, 106.80°E, Java Island, Indonesia; host: phoretic/dwelling host: freshwater crab Parathelphusa sp. ( Gecarcinucidae ); primary host: unknown (most likely fish)] ( Blanchard 1897; Soós 1969; Sawyer 1986);

(3) Batracobdelloides undulatus ( Harding, 1924) comb. nov. [= Placobdella undulata Harding, 1924 ; = Placobdelloides undulata ( Harding, 1924) ; type locality: Colombo Lake [Beira Lake, 6.9294°N, 79.8542°E], Sri Lanka; host: fish Etroplus suratensis (Bloch, 1790) ( Cichlidae )] ( Harding 1924; Soós 1969; Sawyer 1986).

It should be noted that fixed samples of Batracobdelloides often appear as bioculate leeches, because the anterior pair of eyespots is very small and is easily disappeared under the influence of a preservative fluid ( Bolotov et al. 2019). For this reason, the nominal species, listed above, were placed in Placobdella , Helobdella and/or Placobdelloides .