Hygrobates salamandrarum Goldschmidt, Gerecke and Alberti, 2002

Nishikawa, Kanto, Goldschmidt, Tom, Hiruta, Shimpei F. & Shimano, Satoshi, 2020, Taxonomic amendments of Southeast Asian newt species of the genera Pachytriton, Paramesotriton and Laotriton (Amphibia, Urodela, Salamandridae) parasitized by water mites of the subgenus Lurchibates (Hydrachnidia, Hygrobatidae, Hygrobates), Zootaxa 4768 (2), pp. 297-300 : 297-299

Hygrobates salamandrarum Goldschmidt, Gerecke and Alberti, 2002

(Acari, Hydrachnidia, Hygrobatidae ) is the firstknown water mite parasitizing adult newts.

After its description, three further species of newt-parasitizing mites were described and the subgenus Lurchibates Goldschmidt and Fu, 2011 was proposed for the group, now containing four newtparasitizing mites. Until now, each water mite species parasitizes a different newt species ( Table 1), suggesting possible mite-newt co-speciation. In order to test this hypothesis, we need an accurate taxonomy of both of the hosts and parasites. However, the taxonomy of those Asian newt genera known to be parasitized by Lurchibates mites has been substantially revised after the initial description of the H. salamandrarum . To account for these taxonomic changes, we here revise the host-parasite species list and amend the host species name as shown in Table 1.

Hygrobates salamandrarum was collected from the body of Pachytriton labiatus ( Unterstein, 1930) obtained via pet trade ( Goldschmidt et al., 2002). However the identity of this newt species was revised by Nishikawa et al. (2011a). These authors found that the type specimen of Pac. labiatus belonged to a different genus ( Paramesotriton ), and its name therefore changed to Paramesotriton labiatus ( Unterstein, 1930) . By this taxonomic change, the Pachytriton newt that had been considered as “ Pachytriton labiatus ” and from which the mites were collected, came to have no name. Further, Nishikawa et al. (2011a) found that the “ Pachytriton labiatus ” could be separated into two species, and consequently they revived Pachytriton granulosus Chang, 1933 for populations from Zhejiang and Anhui provinces, and newly described Pac. inexpectatus Nishikawa, Jiang, Matsui and Mo, 2011 for those from Guizhou, Henan, and Guangdong provinces and Guangxi Zhuang Autonomous Region. After that, Nishikawa et al. (2011b) revised the taxonomy of Pachytriton , and the Anhui population of Pac. granulosus was described as Pac. feii Nishikawa, Jiang, and Matsui, 2011 and some populations from Guangxi, sympatric to Pac. inexpectatus, were described as Pac. moi Nishikawa, Jiang, and Matsui, 2011.

Unfortunately, the symbiotypes (host newt specimens) of H. salamandrarum were not assigned and the specimens were lost. The specimens originated from the pet-trade, and therefore no locality information is available for them. Judging from the measurements and color pattern from the photos of the newts ( Fig. 1 ), the host most probably can be assigned to be Pac. granulosus Chang, 1933 . At least one of the specimens ( Fig. 1A and C ) is a matured male with swollen cloaca. Its snout-vent length [SVL] can be estimated from the available photos, which contained a scale, as ca. 61mm. This adult male size is within the ranges of P. granulosus (range 59.0– 78.9mm, mean 69.0mm) and P. feii (range 58.5–90.5mm, mean 73.3mm: Nishikawa et al., 2009) but smaller than other species of the genus ( Nishikawa et al., 2011b). Further, the host newts had body proportions more similar to P. granulosus than to P. feii in the ratio of forelimb length versus SVL (male 22.2% and unknown sex 22.6% vs. male mean 23.2% in P. granulosus , but vs. male mean 25.8% and female mean 23.7% in P. feii ) and that of hindlimb length versus SVL (male 24.4% and unknown sex 26.2% vs. male mean 25.3% in P. granulosus , but vs. male mean 29.6% and female mean 28.3% in P. feii [ Nishikawa et al., 2009]). The color pattern is also similar between the host newts and P. granulosus (ventral markings are large and widely occupy the venter and cloacal marking connects with that of ventral tail: see Figs. 4 and 5 in Nishikawa et al., 2009), but not P. feii (markings are small and blotched and cloacal marking does not connect with that of ventral tail: see Fig. 5 in Nishikawa et al., 2011b). We, thus, propose to revise the symbiotypic species of H. salamandrarum as to be Pac. granulosus .

For Hygrobates ancistrophorus Goldschmidt and Koehler, 2007 , the mites were collected from Paramesotriton laoensis Stuart and Papenfuss, 2002 , which has subsequently been transferred to a different genus, Laotriton Dubois and Raffaëlli, 2009 (Frost, 2019) . Thus, the host newt of H. ancistrophorus is now Laotriton laoensis ( Stuart and Papenfuss, 2002) .

Figures

FIGURE 1. Dorsal (A and B) and ventral (C and D) views of host newts from which the type specimens of Hygrobates salamandrarum were collected. Figure A and C show the mature male. Photos were provided by Arne Lindau. Scale shows 10mm.