Epimeriidae Boeck, 1871

d’Acoz, Cédric d’Udekem & Verheye, Marie L., 2017, Epimeria of the Southern Ocean with notes on their relatives (Crustacea, Amphipoda, Eusiroidea), European Journal of Taxonomy 359, pp. 1-553 : 11-14

Family Epimeriidae Boeck, 1871

Epimerinae Boeck, 1871: 103.

Atylinae – Buchholz 1874: 366 (in part).

Epimerinae – Boeck 1876: 227. — Stebbing 1883: 204 (in part).

Epimeridae – G.O. Sars 1883: 26; 1886: 166; 1893: 362 –363. — Stebbing 1888: 876 –877. — Chevreux 1900: 62. — Reibisch 1906: 188.

Epimeriidae – Coleman & J.L. Barnard 1991 a: 255–257. — Coleman 1998b: 216; 2007: 28. — Lörz & Brandt 2004: 179. — Lörz & Held 2004: 4 –15.

Paramphithoidae – Stebbing 1906: 320 (in part); 1908: 191 (in part). — Stephensen 1928: 252 (in part); 1929: 130 (in part). — Chevreux & Fage 1925: 190 (in part). — Gurjanova 1951: 665 (in part); 1955: 187 –188 (in part); 1972: 175 –178 (in part). — Hurley 1957: 3, 5 (in part). — J.L. Barnard 1961: 102 (in part); 1969: 389 (in part). — Bousfield 1979: 363, 378 (in part, discussion); 1982: 265 (in part). — Lincoln 1979: 434 (in part). — Holman & Watling 1983: 31 (in part, discussion). — Andres & Lott 1986: 134 (discussion). — Ledoyer 1986: 854 (in part); 1993: 616 (in part). — Bousfield & Shih 1994: 130 (in part, discussion). — Bousfield & Hendrycks 1995: 5 (in part, key).

‘ Acanthonotozomatidae and Paramphithoidae’ – Karaman & J.L. Barnard 1979: 107 (in part).

Iphimediidae – J.L. Barnard & Karaman, 1991: 378 (in part).

non Atylina [sic] Lilljeborg, 1865: plate p. 18. non Iphimedinae Boeck, 1871: 98 . non Paramphithoidae G.O. Sars, 1883: 25 ; type genus Paramphithoe Bruzelius, 1859: 68 ; type species:

Acanthosoma hystrix Ross, 1835 designated by J.L. Barnard & Karaman 1991: 398. non Acanthonotozomatidae Stebbing, 1906: 210 . non Paramphithoidae – Della Valle, 1893: 557 (discussion). — G.O. Sars 1893: 343 (full description). —

Chevreux 1900: 62.

Composition

Two genera are accepted herein within the Epimeriidae : Epimeria Costa in Hope, 1851 and Uschakoviella Gurjanova, 1955 . Actinacanthus Stebbing, 1888 and Paramphithoe Bruzelius, 1859 are removed from the Epimeriidae , and respectively transferred to the Acanthonotozomellidae Coleman & J.L. Barnard, 1991 and the Paramphithoidae G.O. Sars, 1883 .

Nine subgenera are recognized within Epimeria : Drakepimeria subgen. nov., Epimeria Costa in Hope, 1851; Epimeriella Walker, 1906 ; Hoplepimeria subgen. nov.; Laevepimeria subgen. nov.; Metepimeria Schellenberg, 1931 ; Pseudepimeria Chevreux, 1912 ; Subepimeria Bellan-santini, 1972 and Urepimeria subgen. nov.

Systematic remarks and decisions

The composition of the family Epimeriidae is in a state of flux. Coleman (2007) listed the following genera within the Epimeriidae : Actinacanthus Stebbing, 1888 ; Epimeria Costa in Hope, 1851; Epimeriella Walker, 1906 ; Metepimeria Schellenberg, 1931 ; Paramphithoe Bruzelius, 1859 and Uschakoviella Gurjanova, 1955 . On the other hand, Lörz & Brandt (2004) treated Epimeriella as a junior synonym of Epimeria and questioned the validity of Metepimeria . Metepimeria was initially erected as a monotypic genus for the Magellanic species Epimeria acanthurus , based on a single character state: the absence of dactylus on the palp of the maxilliped. This character state is likely autapomorphic and Metepimeria is relegated herein to the status of subgenus of Epimeria , with a new definition. A recent molecular phylogenetic analysis ( Verheye et al. 2016b) demonstrated that Paramphithoe is unrelated to Epimeria but belongs to the Apherusa / Halirages clade. The senticaudate-type uropods 1–2 and the dissimilar palp of the left and right maxilla 1 (see G.O. Sars 1890 –1895: pl. 130 for Paramphithoe and d’Udekem d’Acoz 2012 for Halirages ) are characteristic of this clade, the second character being interpreted as a putative synapomorphy. The profound differences between Paramphithoe and Epimeria were previously pointed out by Gurjanova (1955: 188) and the affinity of Paramphithoe with the Calliopiidae s. lat. was already perceived by Bousfield (1979: 363). Paramphithoe sensu Stebbing, 1906 is therefore herein formally removed from the Epimeriidae and transferred to the Paramphithoidae G.O. Sars, 1883 , which are re-established.

The study of Verheye et al. (2016b) showed that Alexandrella Chevreux, 1911 , Bathypanoploea Schellenberg, 1939 (Alexandrellinae) , Astyra Boeck, 1871 (Astyrinae) , Dikwa Griffiths, 1974 (Dikwidae) , Acanthonotozomella Schellenberg, 1926 , Acanthonotozomoides Schellenberg, 1931 (Acanthonotozomellidae) and Acanthonotozomopsis Watling & Holman, 1980 (Vicmusiidae) are part of a more inclusive clade including Epimeria . All these families are accepted herein but an alternative could indeed be to merge all taxa related to Epimeria into one large family, which we do not advocate, at least for the time being. The genus Actinacanthus , which was traditionally included within the Epimeriidae (e.g., Coleman 2007; De Broyer et al. 2007), exhibits striking morphological similarities with the Acanthonotozomellidae , such as the presence of a pair of huge sword-like teeth on pereionites just above the insertion of coxae, and a non-incised telson. While convergent evolution cannot be ruled out, it seems more likely that these characters are synapomorphies. Actinacanthus is therefore transferred herein to the Acanthonotozomellidae . The genus Uschakoviella , also traditionally assigned to the Epimeriidae , is provisionally retained within this family, in the absence of evidence against its current taxonomic position.

Nomenclatural remarks

The nomenclatural status of the family Paramphithoidae G.O. Sars, 1883 (previously considered as a junior synonym of the Epimeriidae Boeck, 1871 ) and of the genus Paramphithoe Bruzelius, 1859 (previously considered as an Epimeriidae ) requires discussion. The genus Paramphithoe was created by Bruzelius (1859) for nine unrelated or distantly related species. Stebbing (1895) noted that “the nine species attributed to that genus by its author have since been distributed among half-a-dozen genera, amid which the original genus, from its vagueness, is an abiding source of confusion. It is a wandering star, of which the orbit is difficult to calculate.” The family name Paramphithoidae was introduced, albeit without description by G.O. Sars (1883). According to ICZN (1999 arts. 12.1. and 12.2.4), Paramphithoidae G.O. Sars, 1883 is a valid name because it derives from an available generic name: Paramphithoe Bruzelius, 1859 , an explicit description being not required for family names introduced before 1931. G.O. Sars (1883) did not explicitly define the composition of the Paramphithoidae and he designated no type species for Paramphithoe . He simply listed four species in it: Pleustes panoplus (Kröyer, 1838) (a species included in Paramphithoe by Bruzelius (1859) when he created that genus), Pleustes parvus ( Boeck, 1871) (a probable junior synonym of Pleustes panoplus according to Stebbing (1906)), Paramphithoe brevicornis G.O. Sars, 1883 and Paramphithoe assimilis G.O. Sars, 1883 . All these species are currently considered as members of the family Pleustidae Buchholz, 1874 . G.O. Sars (1883) did not include Paramphithoe hystrix ( Ross, 1835) (under the name Acanthozone cuspidata (Lepechin, 1780)) in the Paramphithoidae G.O. Sars, 1883 but put it in the Epimeriidae Boeck, 1871 .

Ten years later, G.O. Sars (1893) provided a detailed description of the Paramphithoidae , in explicitly restricting it to four genera: Pleustes Spence Bate, 1858 , Paramphithoe Bruzelius, 1859 , Stenopleustes G.O. Sars, 1893 and Parapleustes Buchholz, 1874 , and dealing only with species currently treated as Pleustidae — two of them being part of the original Paramphithoe species of Bruzelius (1859): Paramphithoe pulchella (Kröyer, 1846) and Pleustes panoplus (Kröyer, 1838) . Consistently with his previous study, G.O. Sars (1893) included Paramphithoe hystrix (again under the name Acanthozone cuspidata ) in the Epimeriidae , this time in explicitely listing Acanthosoma hystrix Ross, 1835 (as Acanthosoma hystrix Owen ) in its synonymy. Again, he designated no type species for Paramphithoe .

Stebbing (1906) provided a new definition of the Paramphithoidae conflicting with the previous ones, without citing G.O. Sars (1883, 1893). The Paramphithoidae consisted of Actinacanthus , Epimeria and Paramphithoe . Stebbing (1906) designated no type species for Paramphithoe . He simply stated: “3 accepted species, 1 doubtful”. The three accepted species were P. buchholzi Stebbing, 1906 , P. hystrix and P. polyacantha (J. Murdoch, 1885) and the “doubtful” species P. cuspidata . In other words, only one of the original Paramphithoe species of Bruzelius (1859), namely P. hystrix , was accepted by him in that genus — while the species was clearly excluded from the Paramphithoidae by G.O. Sars (1883, 1893). Stebbing’s (1906) re-definition of Paramphithoe and of the Paramphithoidae was accepted in all subsequent literature, where the family Paramphithoidae was either cited without author’s name (e.g. Barnard 1969) or, more rarely, attributed to Stebbing (1906) (e.g. Bousfield 1979, Coleman & Barnard 1991a). In other words, Stebbing’s (1906) proposal (not a nomenclatural act) was unanimously accepted by the community of amphipodologists as if it was the formal designation of the type species of the genus Paramphithoe ; the statements of G.O. Sars (1883, 1893) were ignored. Finally Barnard & Karaman (1991) designated Acanthosoma hystrix Ross, 1835 as the type species of the genus Paramphithoe — hence also of the family Paramphithoidae .

Just like Stebbing (1906), Coleman & J.L. Barnard (1991a) believed that Paramphithoe sensu J.L. Barnard & Karaman (1991) was a close relative to the genus Epimeria and had to be included in the same family. They re-established the name Epimeriidae Boeck, 1871 for Epimeria , Paramphithoe (and other genera) because it is older than “ Paramphithoidae Stebbing, 1906 ”. It now appears that Paramphithoe is unrelated to Epimeria ( Verheye et al. 2016b) and is nested within the Apherusa / Halirages clade. The family Paramphithoidae has to be re-established for this internally poorly resolved clade including (at least) Apherusa Walker, 1891 , Halirages Boeck, 1871 and Paramphithoe revealed by Verheye et al. (2016b). Additional calliopiid genera (especially from the northern hemisphere) will possibly also have to be transferred to the Paramphithoidae , when more details on their phylogenetic position will be known. Currently, unless ICZN 1999, Article 35.5 on the precedence for names in use at higher rank is invoked, the Calliopiidae can at best be preserved for the genus Calliopius alone, which might be the sister clade of the Paramphithoidae ( Verheye et al. 2016b) , and presents no close affinity with other sequenced genera traditionally included in the Calliopiidae . However in databases, we feel that the ‘ Calliopiidae s. lat.’ should be preserved for all or most genera traditionally included within the Calliopiidae (excluding Apherusa , Halirages and Paramphithoe ) as an ‘adoptive’ artificial family, as long as their phylogenetic and systematic position remains in a too imperfect state of knowledge.

Key to the genera of Epimeriidae

1. Body with or without large dentiform processes, but not homogeneously and densely covered by medium-sized styliform teeth …………………………………… Epimeria Costa in Hope, 1851

– Body homogeneously and densely covered by medium-sized styliform teeth [recorded once, doubtfully, in the Southern Ocean, below 3000 m] ……………… Uschakoviella Gurjanova, 1955