New Genus Name for Lepadichthys lineatus Complex Clingfish
Four species of clingfish have been moved into newly erected genus Rhinolepadichthys. Rhinolepadichthys geminus, heemstraorum, lineatus and polyastrous were all previously included in the “Lepadichthys” lineatus complex but researchers Kyoji Fujiwara, Hiroyuki Motomura, Adam P. Summers, and Kevin W. Conway say that the generic assignment of Lepadicthys lineatus has been contentious since the original description in 1966.
Several authors have instead considered it a member of Discotrema since then, and in their study of Discotrema, Craig and Randall in 2008 briefly discussed the conflicting taxonomic views concerning L. lineatus and noted that “future study may result in its placement in a new monotypic genus.”
In a more recent molecular phylogenetic study of Gobiesocidae, Conway et al. (2020) showed that Lepadichthys is polyphyletic and recovered “L.” lineatus as a close relative of Discotrema and Diademichthys and not the closest relative of any other species of “Lepadichthys” included in that study.
Subsequently, Fujiwara and Motomura (2021) demonstrated that specimens previously identified as “L.” lineatus comprised four distinct species, three of which were described as new – “L.” geminus “L.” heemstraorum, and “L.” polyastrous).
Fujiwara and Motomura (2021) also provided a redescription of “L.” lineatus, which they identified as a senior synonym of “L.” caritus Briggs, 1969, and defined the “L.” lineatus complex (including “L.” lineatus, “L.” geminus, “L.” heemstraorum, and “L.” polyastrous) based on unique characters of the snout and lips.
Now, Fujiwara, Motomura, Summers, and Conway have gone one step further with their work, erected the new genus Rhinolepadichthys, and moved the four species in question into there.
“Detailed investigation of external morphology and osteological anatomy of the new genus and related genera suggests that Rhinolepadichthys represents the sister genus to Discotrema, based on the following putative synapomorphies…” the paper published in the journal Vertebrate Zoology states.
“Reexamination of materials of the poorly known genus Unguitrema, considered a close relative of Discotrema, revealed no morphological differences between the two genera. Unguitrema therefore represents a junior synonym of Discotrema.”
About clingfish
There are 55 genera and 187 species of Clingfishes and singleslits within the family Gobiesocidae. They inhabit shallow fresh, brackish and saltwater environments in the tropical and temperate waters of the Atlantic, Indian and Pacific Oceans and some are associated with invertebrate hosts such as sea urchins or crinoids.
The Doubleline clingfish, Rhinolepadichthys lineatus (Image A) lives on the crinoids Lamprometra klunzingeri and Capillaster multiradiata and feeds on the pinnulae of its hosts – Fishbase
The Urchin clingfish, Diademichthys lineatus, (Image F) is sometimes available in the marine aquarium trade.
Citation
Fujiwara K, Motomura H, Summers AP, Conway KW (2024) A new generic name for the “Lepadichthys” lineatus complex with a rediagnosis of Discotrema, a senior synonym of Unguitrema, and comments on their phylogenetic relationships (Gobiesocidae: Diademichthyinae). Vertebrate Zoology 74: 279-301. https://doi.org/10.3897/vz.74.e113955
Image credits
Main image Rhinolepadichthys geminus (Okinoerabu Islands, Amami Islands, Japan: K. Uehara
Second image A Rhinolepadichthys lineatus (Oman: J. Randall); B Rhinolepadichthys geminus (Anilao, Philippines: J. Eyre); C Rhinolepadichthys geminus (Okinoerabu Islands, Amami Islands, Japan: K. Uehara); D Discotrema crinophilum (Amami-oshima Island, Amami Islands, Japan: KPM-NR 78755, K. Uchino); E Lepadichthys frenatus (Lord Howe Island, Australia: J. Eyre); F Diademichthys lineatus (Lembeh Strait, Indonesia: KPM-NR 147468, K. Uchino). All images except F with sides reversed.
