Eumicrotremus Gill 1862

Genus Eumicrotremus Gill, 1862b

Eumicrotremus Gill, 1862b: 330 (type species: Cyclopterus spinosus Fabricius, 1776).

Cyclopteroides Garman, 1892: 37 (type species: Cyclopteroides gyrinops Garman, 1892).

Lethotremus Gilbert, 1896: 449 (type species: Cyclolumpus muticus Gilbert, 1896).

Cyclolumpus Tanaka, 1912: 86 (type species: Cyclopteropsis asperrimus Tanaka, 1912).

Cyclopteropsis Soldatov & Popov, 1929: 240 (type species: Eumicrotremus bergi Popov, 1929). Cyclopterocottus Popov, 1930: 74 (type species: Eumicrotremus brashnikowi Schmidt, 1904).

Microancanthus Voskoboinikova, 2015: 217 (type species: Microancanthus tokranovi Voskoboinikova, 2015). Georgimarinus Voskoboinikova & Nazarkin, 2015: 630 (type species: Cyclopteropsis barbatus Lindberg & Legeza, 1955).

Diagnosis. Head and body lacking tentacles; some species with bony elements on head and body; one or two foramina present on anterodorsal portion of prootic; mesial process of hyomandibula receiving adductor hyomandibulae; first dorsal fin visible; end of gill slit situated above level of base of uppermost pectoral fin ray.

Remarks. The synonymy of Cyclopteropsis Soldatov & Popov, 1929, Eumicrotremus Gill, 1862b, Lethotremus Gilbert, 1896, and Georgimarinus Voskoboinikova & Nazarkin, 2015 is proposed here on the basis of inferred phylogenetic relationships (see “Ranking at subfamilial and generic levels”). Microancathus Voskoboinikova, 2015 is also regarded to be a junior synonym of Eumicrotremus owing to comparison of description of the type species of the former and synapomorphies supporting cyclopterid clades inferred here. The name Eumicrotremus is considered the valid name for the genus, having priority over the others. As redefined, Eumicrotremus is distinguished from the other three valid genera in having a visible first dorsal fin, and lacking tentacles on the head and body.

Tanaka (1912) established the genus Cyclolumpus for Eumicrotremus asperrimus, although it has since been regarded as a junior synonym of Eumicrotremus (Lindberg & Legeza, 1955). The present phylogenetic analysis included E. asperrimus in clade B2, which included all examined Eumicrotremus (and Lethotremus). Accordingly, Cyclolumpus is treated as a junior synonym of Eumicrotremus, following previous studies.

Garman (1892) established the genus Cyclopteroides based on Eumicrotremus gyrinops Garman, 1892. However, this genus was also regarded as a junior synonym of Eumicrotremus by Lindberg & Legeza (1955). Garman’s (1892) original description of E. gryinops included: “Skin covered with mucus, with four series of very small, distant, one to eight spined tubercles on each side”, a description closely in agreement with a diagnostic character of Eumicrotremus [head and body (or body only) having some or many tubercles] as redefined here. In addition, although E. gyrinops was not included in the phylogenetic analysis, it was confirmed by examination of a single specimen during this study that the species has many small tubercles on the body. Therefore, the genus Cyclopteroides is treated as a junior synonym of Eumicrotremus, following previous studies.

The genus Cyclopterocottus was established by Popov (1930) for Eumicrotremus brashnikowi Schmidt, 1904, although it has become regarded as a junior synonym of Cyclopteropsis (e.g., Ueno, 1970; Mecklenburg & Sheiko, 2003; Nelson, 2006; this study). Lindberg & Legeza (1955) described E. brashnikowi as having “Spinous plates having cover side of body, nap, region of cheek”, also closely in agreement with a diagnostic character of Eumicrotremus (see above). Although E. brashnikowi was not examined during the present study, the genus Cyclopterocottus is treated as a junior synonym of Eumicrotremus.

Voskoboinikova (2015) established the genus Microancanthus for M. tokranovi Voskoboinikova, 2015 (type species) and Eumicrotremus fedorovi Mandrytsa, 1991, being characterized from other cyclopterids by the following unique characters: a single pore on the infraorbital sensory canal; flat or hemispherical tubercles (as bony plaques) on the body, with numerous small spines; the opercle with a conspicuous notch on its posterior edge; and an S-sharped subopercle. However, although the above species were not available for examination during the present study, M. tokranovi, at least, has sensory tubes on the lower jaw (Voskoboinikova, 2015: fig. 5B), which supports the monophyly of clade G5 (including E. orbis, E. spinosus, “ Lethotremus ” awae and “ L.” muticus) (autapomorphic character 32-1), as recognized in this study. Accordingly, recognition of Microancanthus must result in Eumicrotremus being paraphyletic. Therefore, Microancanthus cannot be recognized from a cladistic perspective and is synonymized under Eumicrotremus in this study, although the monophyly of E. tokranovi and E. fedorovi is supportable based on the above mentioned autapomorphies.

Voskoboinikova & Nazarkin (2015) established the genus Georgimarinus for Eumicrotremus barbatus (Lindberg & Legeza, 1955). They considered that the genus is characterized by unique derived characters: i.e., teeth in the outer row at the symphysis of the premaxilla fused with the premaxilla; teeth at the symphysis of the dentary fused among themselves and with dentary and forming the regular cutting edge; numerous barbs present on the head and body; and the bony plaques located in centers of connective tissue tubercles leaving the edges free. The present study examined this species and also found anterior teeth on the premaxilla and dentary fused with each other and the supporting bones, and these characters were recognized as autapomorphies of the species. However, E. barbatus was inferred to be deeply nested within clade D2 including Eumicrotremus and Cyclopleropsis, and the former genus becomes paraphyletic if Georgimarinus is regraded as valid. Therefore, following the cladistic methodology, the present study synonymizes Georgimarinus under Eumicrotremus.

The genus Eumicrotremus includes the following 25 valid species, seven and two species, respectively, having been previously included in Cyclopteropsis and Lethotremus: Eumicrotremus andriashevi Perminov, 1936, Eumicrotremus awae (Jordan & Snyder, 1902), Eumicrotremus asperrimus (Tanaka, 1912), Eumicrotremus barbatus (Lindberg & Legeza, 1955), Eumicrotremus bergi (Popov, 1929), Eumicrotremus brashnikowi (Schmidt, 1904), Eumicrotremus derjugini Popov, 1926, Eumicrotremus fedorovi Mandrytsa, 1991, Eumicrotremus gyrinops (Garman, 1892), Eumicrotremus inarmatus (Mednikov & Prokhorov, 1956), Eumicrotremus jordani (Soldatov, 1929), Eumicrotremus lindbergi (Soldatov, 1930), Eumicrotremus mcalpini (Fowler, 1914), Eumicrotremus muticus (Gilbert, 1896), Eumicrotremus orbis (Günther, 1861), Eumicrotremus pacificus Schmidt, 1904, Eumicrotremus popovi (Soldatov, 1929), Eumicrotremus phrynoides Gilbert & Burke, 1912, Eumicrotremus schmidti Lindberg & Legeza, 1955, Eumicrotremus soldatovi Popov, 1936, Eumicrotremus spinosus (Fabricius, 1776), Eumicrotremus taranetzi Perminov, 1936, Eumicrotremus tartaricus Lindberg & Legeza, 1955, Eumicrotremus terraenovae Myers & Böhlke, 1950 and Eumicrotremus tokranovi (Voskoboinikova, 2015) (see Lindberg & Legeza, 1955; Ueno, 1970; Parin et al., 2002; Mecklenburg & Sheiko, 2003).