Placobdelloides Sawyer, 1986

Genus Placobdelloides Sawyer, 1986 View in CoL View at ENA gen. rev.

Type species. Clepsine multistriata Johansson, 1909 (by original designations)

Differential diagnosis. Medium-sized leeches (length up to 40 mm; Oosthuizen 1979); one pair of eyespots on III; body with 70 annuli, mid-body somites triannulate; dorsum with six rows of conical papillae at a2 and with multiple small, irregularly arranged papillae on each annulus; mouth pore is terminal; one or two pairs of compact salivary glands; esophageal glands present; seven pairs of crop caeca (2nd to 6th pairs of crop caeca each with three lobes); six pairs of testisacs; the gonopores separated by two annuli: male gonopore on XI a3 / XII a1, female gonopore on XII a2 / XII a3; posterior sucker of large or moderate size, circular, ventrally directed. Phylogenetically, this genus is sister to the Marsupiobdella lineage ( Figure 7).

Distribution. Africa, Madagascar, Yemen, Malaysia, and Singapore ( Oosthuizen 1979; Bolotov et al. 2022b; Bolotov et al. 2023a).

List of species. Apparently, Placobdelloides s. str. contains two reptilian-associated African species, that is, Pl. multistriatus ( Johansson, 1909) [the type species of the genus; continental Africa, Madagascar, and Yemen; host: turtles, terrapins, and crocodiles] and Pl. fimbriatus ( Johansson, 1909) [ Uganda, Kenya, Nigeria; host: crocodiles] ( Moore 1939; Cott 1961; Oosthuizen 1979; Oosthuizen 1991; Bolotov et al. 2022b; Bolotov et al. 2023a). Morphological features of Pl. stellapapillosus Govedich, Bain & Davies, 2002 [ Singapore and Malaysia; host: turtles, crocodiles, and gavials] partly agree with the diagnosis of this genus (one pair of eyespots, one pair of compact salivary glands, six pairs of testisacs, two annuli between the gonopores, seven pairs of lobed crop caeca) ( Sawyer 1986; Govedich et al. 2002; Neely et al. 2017). Conversely, two specific traits, that is, the position of eyespots on I or II and the presence of unique star-shaped papillae on its dorsum, indicate that the generic placement of this species needs future research based on the DNA sequence data.

Hosts. Crocodiles, gavials, turtles, and terrapins serve as primary hosts (reptilian-associated leeches). Water bugs ( Hemiptera ) were recorded as phoretic host for the two African species ( Table 3).

Comments. This genus in its original understanding ( Sawyer 1986) was a paraphyletic group ( Bolotov et al. 2022b). Here, four Placobdelloides species transferred to Palaemobdella gen. nov. (two species) and Batracobdelloides (two species) (see the corresponding accounts above for detail). An African member of the genus, Placobdelloides jaegerskioeldi ( Johansson, 1909) , represents a distant phylogenetic lineage and was recently placed in the monotypic genus Hippobdelloides Bolotov & Pešić, 2025 ( Bolotov and Pešić 2025).

Turtle-associated Placobdelloides leeches from tropical Asia were also found to be a separate clade that was described as the genus Orientobdelloides Bolotov, Eliseeva & Kondakov, 2022 ( Bolotov et al. 2022b). Three former members of Placobdelloides were placed in the genus Orientobdelloides as follows: Or. siamensis (Oka, 1917) [the type species of the genus], Or. sirikanchanae (Trivalairat, Chiangkul & Purivirojkul, 2019) , and Or. tridens ( Chiangkul, Trivalairat, Kunya & Purivirojkul, 2021) . Based on morphological features, six additional nominal species should be considered representatives of this group:

(1) Orientobdelloides emydae ( Harding, 1920) comb. nov. [= Placobdella emydae Harding, 1920 ; = Placobdelloides emydae ( Harding, 1920) ; composite type locality: ‘Station No. 52, 4-9 mi. E.1/ 2N. of Patsahanipur, Lake Chilka’; ‘outskirts of Calcutta’; ‘Gatiagurh, Dist. Hughly, Bengal’; ‘R. Mahanaddi, Sambalpur, Orissa’; ‘near Purulia, Chota Nagpur Div., Bihar’; ‘Nagpur, C.P.’, India; range: India; host: turtle Lissemys punctata (Lacépède, 1788) ( Trionychidae )] ( Harding 1920; Harding and Moore 1927; Sawyer 1986);

(2) Orientobdelloides indicus (Baugh, 1960) comb. nov. [= Placobdella indica Baugh, 1960 ; = Placobdelloides indica (Baugh, 1960) ; type locality: ‘a rocky pool ‘Sitkundi’ in Kalipahar about 7 miles S.W. of Monghyr Dist. (Bihar)’, approx. 25.3105°N, 86.5052°E, India; range: India; host: unknown (likely freshwater turtles)] ( Baugh 1960b; Sawyer 1986);

(3) Orientobdelloides inleanus ( Oka, 1922) comb. nov. [= Glossiphonia inleana Oka, 1922 ; = Placobdella inleana ( Oka, 1922) ; type locality: ‘Fort Stedman, Inle Lake’, approx. 20.5773°N, 96.9436°E, Myanmar; range: Myanmar; host: turtle Cyclemys oldhami shanensis Annandale, 1918 ( Geoemydidae )] ( Oka 1922; Harding and Moore 1927);

(4) Orientobdelloides guangdongensis ( Tan & Liu, 2001) comb. nov. [= Hemiclepsis guangdongensis Tan & Liu, 2001 ; type locality: Guangzhou City, approx. 23.02°N, 113.03°E, Guangdong Province, China; range: Pearl River basin, South-East China; host: turtle Cuora amboinensis (Daudin, 1801) ( Geoemydidae )] ( Tan and Liu 2001);

(5) Orientobdelloides bancrofti ( Best, 1931) comb. nov. [= Helobdella bancrofti Best, 1931 ; = Placobdella bancrofti ( Best, 1931) ; = Placobdelloides bancrofti ( Best, 1931) ; type locality: Burnett River, Queensland, Australia; range: Australia; host: turtles Emydura macquarii krefftii (Gray, 1871) and Myuchelys latisternum (Gray, 1867) ( Chelidae )] ( Best 1931; Sawyer 1986; Govedich 2001; McKenna et al. 2005);

(6) Orientobdelloides octostriatus ( Grube, 1867) comb. nov. [= Clepsine octostriata Grube, 1867 ; = Placobdelloides octostriata ( Grube, 1867) ; type locality: Rockhampton, approx. 23.3739°S, 150.5128°E, Queensland, Australia; range: Australia; host: turtles Emydura australis (Gray, 1841) and Chelodina burrungandjii Thomson, Kennett & Georges, 2000 ( Chelidae )] ( Grube 1867; Grube 1871; Govedich 2001; Tucker et al. 2005).

Two nominal species, that is, Orientobdelloides tridens and Or. indicus , are characterized as having trident-shaped (trilobate) crop caeca ( Figure S6). This pattern was considered a unique diagnostic trait of the first species ( Chiangkul et al. 2021a; Kambayashi et al. 2024). However, Orientobdelloides tridens differs from Or. indicus by having one pair of compact salivary glands (vs. two pairs) ( Figure S6). It should be noted that Orientobdelloides tridens was recently discovered from Java, Indonesia (Kambayashi et al. 2024). This record reveals that the range of this turtle-associated species is broader than it was initially expected ( Chiangkul et al. 2021a), although populations of this leech on Java and in Thailand are rather distant phylogenetically (the uncorrected COI p-distance = 5.2 %) (Kambayashi et al. 2024). The data, outlined above, indicate that there may be a species complex of leeches with trident-shaped crop caeca, containing Or. tridens, Or. indicus , and some additional species.

Next, Placobdelloides okadai ( Oka, 1925) [= Hemiclepsis okadai Oka, 1925 ; = Placobdella okadai ( Oka, 1925) ] was described based on a composite type series that contains specimens collected from the Ryukyu Archipelago of Japan [Amami Ōshima Island and Shuri on Okinawa Island; host: frogs Limnonectes namiyei (Stejneger, 1901) ( Dicroglossidae ) and Babina holsti (Boulenger, 1892) ( Ranidae )] and from North China (Beijing; host: unspecified turtle) ( Oka 1925; Soós 1969; Sawyer 1986). The description and illustrations of the species are mostly based on the Japanese specimens ( Oka 1925) and, hence, the type locality could be restricted to the two islands of the Ryukyu Archipelago. According to the protologue, this nominal species is characterized by the following combination of characters: small leeches (length up to 15 mm); live animal has uniform dark olive ground color, without bands and spots; one pair of eyespots on II (very close to each other); dorsum smooth; body with 66 annuli: somites I-IV uniannulate, V-VI biannulate, VII-VIII 'transitional from biannulate to triannulate' [calculated as biannulate by Oka], IX-XXV triannulate, XXVI biannulate, XXVII uniannulate; the mouth pore is terminal; seven pairs of branched crop caeca; six pairs of testisacs; the gonopores separated by two annuli: male gonopore on XI a3 / XII a1, female gonopore on XII a2 / XII a3; very large posterior sucker (diameter as great as the body width) ( Oka 1925). The salivary glands are not described. Oka (1925) also noted that this species externally resembles the biannulate species Oligobdella orientalis ( Oka, 1925) [synonym of Torix tagoi ( Oka, 1925) ; Kambayashi and Nakano 2023] and Oligobdella biannulata (Moore, 1900) [now Placobdella biannulata ; Siddall et al. 2005]. Indeed, most features of Placobdelloides okadai agree with the diagnosis of the genus Torix Blanchard, 1893 , except for triannulate mid-body somites (vs. biannulate) ( Kambayashi and Nakano 2023). In our opinion, Placobdelloides okadai could be considered a member of the latter genus, morphologically representing a transitional form from triannulate to biannulate condition. It is known that triannulate and biannulate species may occur within one genus (e.g., Placobdella biannulata ) ( Siddall et al. 2005). As a conclusion, we propose a new combination as follows: Torix okadai ( Oka, 1925) comb. nov. It can be considered endemic to the Ryukyu Islands and may represent a sister lineage to Torix tagoi , although this preliminary hypothesis needs to be confirmed in the future by means of a DNA-based approach. The part of the type series of this nominal species collected from the mouth of a turtle in Beijing may belong to a species of the genus Mooreotorix Lukin, 1976 . In turn, records of ‘ Placobdelloides okadai ’ from Honshu ( Yamauchi et al. 2008) most likely belong to Torix tagoi (see Kambayashi and Nakano 2023). A specimen of ‘ Placobdella okadai ’ from Nanking, China described by Moore (1930) may belong to an additional species of Torix .

Finally, morphological features of Placobdelloides bdellae ( Ingram, 1957) and Placobdelloides maorica ( Benham, 1907) from Tasmania and New Zealand, respectively ( Benham 1907; Ingram 1957; Mason 1974; Sawyer 1986; Govedich 2001) do not fully consistent with the differential diagnosis of Placobdelloides s. str. (see above). In particular, these species can be distinguished from representatives of the latter genus by having a greatly enlarged and anteriorly directed first pair of crop caeca (vs. small, laterally or antero-laterally directed) ( Figure S7). Therefore, we propose a new genus to incorporate these two species (see below).