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The Siamese shield leech (Placobdelloides siamensis) is one of the external parasites found in snail-eating turtles (Malayemys macrocephala and Malayemys subtrijuga). It has a muscular proboscis with numerous needle-like tips for penetrating the host body, and its consumption of blood and tissues differs from arhynchobdellid leeches that use a jaw tearing strategy. Dorsal coloration is attributed to pigment cells under the dorsal muscular layer, while the absence of pigment on the ventral side indicates transparency. Morphology and histology reveal the parental care behavior of this glossiphoniid leech, with the juveniles using their caudal sucker to attach an annulus around the ventral groove of the parent. Further, the histological structure of the posterior part demonstrates the presence of four contributing muscle fibers and chloragogen cells on the caudal sucker. Hence, this first report provides increasing morphological and histological knowledge of this leech for use as a representative model of a glossiphoniid leech.

A new glossiphoniid leech species, Placobdelloides tridens sp. n., is discovered on the Malayan Giant Turtle (Orlitia borneensis) at the Nakhon Ratchasima Zoo in Thailand. The morphological study of this new species revealed that it is distinguished from P. siamensis, a turtle leech species that can be found commonly in Thailand. Placobdelloides tridens presented the following diagnostic morphological characteristics: a pear-shaped and triannulate body, well-developed rod-like papillae on the dorsal surface, smooth posterior and anterior suckers with nominal pits inside, a single pair of dark contiguous eyes, light yellow-brown to greenish dorsal color, absence of median line, male and female gonopore separated by a single annulus and a unique trident shape at the tip of the crop ceca. The phylogenetic relationships of P. tridens sp. n., was clarified, and shown to be a sister clade to the P. siamensis and P. sirikanchanae clade. Furthermore, this is a new host record for P. siamensis, which was found on O. borneensis, Batagur affinis and B. borneoensis in the Khao Kheow Open Zoo, Chonburi, Thailand.

A new snail-eating leech, Batracobdelloides bangkhenensis sp. n., was discovered at Kasetsart University, Bangkhen Campus, Bangkok, Thailand. This species is found free living in the benthic zone of ponds; feeds on freshwater snails, including Bithynia siamensis siamensis, Indoplanorbis exustus, Radix rubiginosa, Physella acuta, and Pomacea canaliculata; and uses a shell as a shelter during the parental care period, with a colony of 7-15 juvenile individuals held on the venter inside the shell of host. Batracobdelloides bangkhenensis displays distinct morphological characters, including a rice-shaped body showing transparency, cephalization, two eye pairs merged on somite III, an anterior sucker twice as large as the cephalic region, a central mouth in the anterior sucker, seven light brown transverse rows in the neck region, absent dorsal papillae, rich green pigments on the dorsum, a male gonopore on XIIa2/XIIa3 (27-28), a female gonopore on XIIIa1/XIIIa2 (29-30), and diffuse aggregations of minute, spherical salivary glands in the neck region. Comparisons of the COI and COI-ND1 genes showed a monophyletic clade for Batracobdelloides, and the phylogenetic tree of the COI gene also indicated that B. bangkhenensis is distinct from other species in the genus, with strong support values.

The Siam Shield Leech, Placobdelloides siamensis, is a common leech found on Malayemys turtles in Thailand. Sixty Snail-eating Turtles (29 Malayemys macrocephala and 31 M. subtrijuga) were caught over twelve months (February 2017 – January 2018) to determine host characteristics (body size, weight and sex), parasitism (prevalence, intensity and density) and seasonal aquatic environmental factors (conductivity, nitrate nitrogen, dissolved oxygen, pH, salinity and total dissolved solids). There was no significant difference of infection rate between species and sex in both turtle species. Leech prevalence indicated that all turtle individuals were infected throughout year, while the infection rate was significantly higher in larger and heavier turtles mainly on the carapace with an average number of leech approximately 474.80 ± 331.38 individuals for individual host infection and 76.53 ± 20.27 individuals for infection per 100 g body weight. The high level of leech parasitism also caused a rot wound and shell hole which caused the host to die. Aquatic environmental factors did not influence the infection of leeches in both turtle species. Therefore, the factors that influenced the infection rate of P. siamensis were based on only host body size and weight without effect from season. In addition, this study also showed two new hosts, including Cyclemys oldhamii and Heosemys grandis and the widespread distribution from northern, north-eastern, western, central and southern Thailand were reported.

In Thailand, five species of Acanthosaura have been recorded so far, including Acanthosaura armata from the southern region, A. cardamomensis from the eastern region, A. crucigera from the western region, A. lepidogaster from the northern region and A. phuketensis from the Phuket Island and south-western region. However, comprehensive studies of diversity patterns and distribution of Acanthosaura are still lacking in some areas and need further information for designating areas of special conservation importance and nature protection planning in Thailand. Acanthosaura aurantiacrista is a new species of long-horned lizard of the genus Acanthosaura from northern Thailand. It is distinguished from all other species of Acanthosaura by a dagger-like nuchal spine with yellowish-orange colouration in females, bright yellow colouration in males and a combination of other morphological characters: a greater tail length to snout-vent length ratio; a larger postorbital spine, nuchal spine, dorsal spine and occipital spine compared to its head length; a smaller diastema to snout-vent length ratio; a greater number of subdigital lamellae on the fourth finger and fourth toe; and a larger gular pouch than other Acanthosaura species. Analysis of mitochondrial ND2 gene sequences revealed a sister clade between the A. aurantiacrista lineage and the A. crucigera lineage with a 100% probability of divergence, according to Bayesian analysis and strong support value for Maximum Likelihood analysis. The pairwise distance ranged from 13.8-15.0% between A. aurantiacrista and A. cardamomensis, 10.9-14.5% between A. aurantiacrista and A. crucigera and 0-1.2% amongst A. aurantiacrista populations. The discovery of this lizard increases the known endemic herpetological diversity and underscores the importance of conservation in the mountain rainforest region of northern Thailand.

A new species of glossiphoniid leech,Placobdelloides sirikanchanaesp. nov., is reported in the Asian leaf turtle (Cyclemys dentata) and the dark-bellied leaf turtle (C. enigmatica) from Songkhla Province, southern Thailand. The examination of morphological characters revealed that this new species is similar toP. siamensis(Oka, 1917), a common turtle leech species found in Thailand.Placobdelloides sirikanchanaesp. nov.demonstrates distinct morphological characters, with an elongated, narrow body, 13–17 well-developed knob papillae on each annulus, dark brown to greenish dorsal color with a crimson median line, the absence of a scarlet dot, different male and female gonopore distributions, a rough posterior sucker with a random pit distribution, and 104–115 eggs per clutch. The phylogenetic relationships of COI-ND1 genes were clarified and shown to be distinct from those ofP. siamensis. Additionally, habitat preferences tended toward low oxygen conditions such as puddles or water patches on rubber plantations.

The Siamese shield leechPlacobdelloides siamensis(Oka, 1917) Sawyer, 1986 (Euhirudinea: Glossiphoniidae) was collected from five new host species, Southeastern Asian Box Turtle (Cuora amboinensis), Yellow-headed Temple Turtle (Heosemys annandalii), Malayan Snail-eating Turtle (Malayemys macrocephala), Mekong Snail-eating Turtle (M. subtrijuga), and Khorat Snail-eating Turtle (M. khoratensis) and was found for the first time in Udon Thani, Thailand. Examination of live leeches provided, for the first time, data on coloration and the combination of parental care behavior, both carrying cocoons and attaching cocoons to the substrate. This species was separated from its congeners based on the following characters: one pair of eyes; spines at proboscis subterminal; mouth terminal on oral sucker; absent plaque in neck region; gonopores located in furrow and separated by two annuli; distinctly triannulated mid-body segments; crop with seven pairs and branched caeca; caudal sucker slightly over half of maximum body width; and strongly dorsal papillae. Phylogenetic relationships based on the COI and ND1 genes were clarified and demonstrated that the species is distinct from others. The original description was amended and the taxonomic history is discussed.