Palaemobdella Bolotov, 2025

Genus Palaemobdella Bolotov gen. nov.

Figure S5 https://zoobank.org/ urn:lsid:zoobank.org:act:D085957B-0D0A-47C4-8DCF-DE6629AA83DE

Type species. Placobdella ornata Oka, 1929 [= Placobdella okai Soós, 1969 ; replacement name that is rejected by us based on Art. 59.4 of the Code (ICZN 1999)].

Differential diagnosis. Small leeches (length up to 12 mm); one pair of cup-shaped (sometimes triangular or round) eyespots on II (in some cases, eyespots are invisible but can be detected histologically as aggregations of visual cells); characteristic dorsal pigmentation patterns with deep chocolate brown ground color, yellow or white longitudinal medial band and lateral yellow or white band or large spots, two or four series of yellow or white spots at a2 (outer paramarginal or outer paramarginal and outer paramedian position); posterior sucker with yellow or white edge and a series of light spots along the margin ( Figure S5); body with 66-67 annuli, mid-body somites triannulate; dorsum is densely covered with small, closely set papillae; mouth pore is subterminal; one pair of compact salivary glands; seven pairs of crop caeca; six pairs of testisacs; gonopores separated by two annuli: male gonopore on furrow XI a3 / XII a1 and female gonopore on furrow XII a2 / XII a3 ( Palaemobdella horai ) or male gonopore on XI a3 and female gonopore on XII a2 ( Palaemobdella ornata ); posterior sucker is small, circular, ventrally directed. Phylogenetic data are not available.

Etymology. The name of this genus is combined from two parts: ‘ Palaemo ’ (reference to its crustacean hosts, the family Palaemonidae ) and ‘ bdella ’ (leech in Greek).

Distribution. The new genus seems to have a disjunctive range ( Baugh 1960a; Lai and Chen 2010). In particular, there are records from India (known only from a small lake in West Bengal) and Taiwan (known from a few localities in the middle and southern part of the island) ( Figure 12). However, we assume that some additional species of this genus may occur within a continuous gap between India and Taiwan. These inconspicuous shrimp-associated leeches might have been overlooked by researchers, as it was the case for a diverse assemblage of mussel-associated leeches ( Bolotov et al. 2019).

List of species. Palaemobdella ornata ( Oka, 1929) gen. & comb. nov. [ Taiwan] and Pe. horai (Baugh, 1960) comb. nov. [ India] ( Table 3).

Hosts. Freshwater shrimps ( Palaemonidae ; phoretic/dwelling host) and fishes ( Cyprinidae and Synbranchidae ; primary host) ( Baugh 1960a; Lai and Chen 2010).

Comments. Previously, the two shrimp-associated species of the new genus were placed in Placobdelloides (see Sawyer 1986) but they differ from its members by the lack of esophageal glands, the smaller number of annuli (66-67 vs. 70-71), the position of eyespots on II, and a very specific dorsal pigmentation patterns.