Taxonomic Notes and Nomenclatural Corrections on Four Sphaeromatid Isopod Generic Names (Crustacea: Isopoda: Sphaeromatidae)

Abstract

Details regarding the synonymy of Nesaea Leach, 1814 and Dynamene Leach, 1814 are given and a type species is selected for Dynamene. The genus Heteruropus Verhoeff, 1942 is shown to be the senior objective synonym of Harrieta Kensley, 1987 and an expanded synonymy list for the type species, Heteruropus faxoni (Richardson, 1905) is provided.

1. Introduction

As Chief Taxonomic Editor of Isopoda for WoRMS (www.marinespecies.org access data 20 July 2023), I sometimes come across species entries that need correction and/or additional context. Two such nomenclatural problems involve the sphaeromatid genera Nesaea Leach, 1814 [1], Dynamene Leach, 1814 [1], Harrieta Kensley, 1987 [2], and the long-overlooked Heteruropus Verhoeff, 1942 [3]. As it is the policy of WoRMS not to make taxonomic changes in the database without a basis in published literature, coupled with the limitations of including explanatory text within taxon entries, it is necessary to publish on these findings here. Substantial details about the convoluted history of Nesaea and Dynamene are given, a type species is selected for Dynamene, and the genera Heteruropus and Harrieta are shown to be objective synonyms. An expanded synonymy list for Heteruropus faxoni (Richardson, 1905) [4] is also provided.

2. Materials and Methods

References and taxonomic information were obtained from WoRMS (marinespecies.org) and the Biodiversity Heritage Library (www.biodiversitylibrary.org). Note that the synonymy list for Harrieta faxoni does not contain any “grey literature” (government documents or reports); a number of such reports can be found online, but the veracity of the species identifications therein is unknown.

3. Results

Taxonomy

Family Sphaeromatidae Latreille, 1825 [5]

Genus Dynamene Leach, 1814 [1]

Nesaea Leach, 1814: 387, 405, 433 [1] (type species: Oniscus bidentatus Adams, 1800 by monotypy [6]).

Dynamene Leach, 1814: 433 (characters given; no included species) [1].

Naesea Leach, 1814: 405 (lapsus?) [1].

Dynamene Leach, 1815: 353, 368 (characters given; no included species) [7].

Naesa Leach, 1815: 353, 367 [7].—Leach, 1818: 342 (unjustified emendation) [8].

Nesa Leach, 1818: 342 (lapsus?) [8].

Dynamene Leach, 1818: 343–344 (three species included) [8].

Type species. Dynamene montagui Leach, 1818 by present designation (=Dynamene bidentatus (Adams, 1800); see below).

Other species. Dynamene bicolor (Rathke, 1836), D. bidentata (Adams, 1800), D. bifida Torelli, 1930, D. curalii Holdich & Harrison, 1980, D. edwardsi (Lucas, 1849), D. magnitorata Holdich, 1968, D. ramuscula Baker, 1908, D. tubicauda Holdich, 1968 (Boyko et al., 2023) [9].

Remarks. Leach [1] listed two species names under Nesaea: “Oniscus bidentatu [sic], Linnaean Transactions” and “Naesea [sic] bidentatas [sic], Leach’s MSS”. The former is a cryptic reference to the paper of Adams [6], published in the Transactions of the Linnean Society; this was made clear in Leach [7] where Adams’ paper was specifically cited. Oniscus bidentatus Adams, 1800 is therefore the type of Nesaea by monotypy. Naesea appears to be a typographical error (or Leach changed his mind about how the genus name should be spelled as Naesea was listed as manuscript spelling in synonymy with Nesaea); all subsequent authors have used Nesaea as the correct spelling of the genus. Leach [7] modified the spelling of the genus to Naesa, perhaps to avoid homonymy with Nesaea Lamouroux [10] but, as pointed out by Holdich [11], he did not expressly state this and Naesa is therefore an unjustified emendation. Most authors who noted that Nesaea was a junior homonym (e.g., [12,13]) did not specify by what name it was preoccupied. Nesaea Lamouroux, 1812 [10] is the senior homonym of Nesaea Leach, 1814 [1], as the name is one originally used for a “polype” (animal) under the category of “Zoophytes flexibles, ou coralligènes non entièrement pierreaux. Troisieme Famille. Les Corallinées (Corallineae)” (=coralline algae) and therefore falls under ICZN Article 2.2 (Names of taxa at some time but not later classified as animals) and competes in homonymy in zoological nomenclature [14]. The fact that Nesaea Lamouroux, 1812 [10] is a rejected name [15] has no bearing on the homonymy.

Dynamene is universally attributed to Leach, 1814 [1] (e.g., [12,16,17,18]), although there were no included species in the genus, as was also true when the name was used for the second time [7]. ICZN Article 12.1 [14] allows Dynamene to be an available name from Leach [1] as descriptive characters were provided. The first time there were any included species in Dynamene was in its third usage [8], so the type species must be selected from one of the three species included in that paper. Leach [8] did not select a type species and the only species names that are eligible to be the type species of the genus are Dynamene montagui Leach, 1818, Dynamene rubra Leach, 1818, and Dynamene viridis Leach, 1818, all of which are synonyms of Dynamene bidentata (Adams, 1800) [12]. Hansen [19] stated that the type species was “Dynamene bidentata (Mont)” (sic; = Oniscus bidentatus Adams, 1800) (see also [12,17]) but that is not correct because Oniscus bidentatus was not among the species names included in Dynamene by Leach [8]. I herein select D. montagui Leach, 1818 as the type species of Dynamene Leach, 1814. Syntypes of D. montagui, D. rubra, and D. viridis are in the collection of the Natural History Museum, London (formerly the British Museum (Natural History), see [20]).

Heteruropus Verhoeff, 1942 [3]

Heteruropus Verhoeff, 1942: 169 [3].

Harrieta Kensley, 1987: 1036–1037 (new synonymy) [2].

Type species. Exosphaeroma faxoni Richardson, 1905 [4] by monotypy.

Other species. None.

Heteruropus faxoni (Richardson, 1905)

Exosphaeroma faxoni Richardson, 1905: xvii, xxxvii, 288, 292, 722, figs. 307, 308 [“Florida”] [4].—Pearse and Wharton, 1938: 640 [Florida panhandle, Gulf Coast] [21].—Menzies & Miller, 1955: 292 [Texas] [22].—Menzies & Glynn, 1968: 12 [list] [23].

“Heteruropus m. (faxoni Rich.—Florida)” Verhoeff, 1942: 169 [generic placement; no new material] [3].

Cymodoce faxoni: Menzies and Miller, 1955: 293–296, figs. 1, 2 [Texas] [22].—Rouse, 1970: 134 [west coast Florida] [24].—Schultz, 1969: 127, Figure 182 [list] [25].—Clark and Robertson, 1982: 47, 49, 51, 54, Figure 18 [Texas] [26]—Menzies and Kruczynski, 1983: 39, 41, 50, 100, 101, Figure 14 [west coast of Florida] [27].—Virnstein et al., 1983: 365, 367, 369 [east coast of Florida] [28].—Harrison and Holdich, 1984: 383 [mention] [29].—Kitting et al., 1984: 147 [Texas] [30].—Howard, 1985: 165–166 [east coast of Florida] [31].—Virnstein & Curran, 1986: 282, 284, 285 [east coast of Florida] [32].—Nelson et al., 2022: 116 [east coast of Florida] [33].

Harrieta faxoni: Kensley, 1987: 1037–1038, Figure 1 [east and west coasts of Florida, Alabama; redescription; generic placement] [2].—Harrison & Ellis, 1991: 940 [list] [18].—Camp et al., 1998: 136 [list] [34].—Rudershausen et al., 2003: 168, 170, 183 [west coast of Florida] [35].—Sheridan, 2004: 450 [Texas] [36].—Barba & Sánchez, 2005: 243–245 [Tamaulipas, Mexico] [37].—McLaughlin et al. (2005): 192 [list] [38].—Burghart et al., 2013: 956, 957, 960, 962 [west coast of Florida] [39].—Walton et al., 2013: 128 [west coast of Florida] [40].—Morelos-Villegas et al., 2018: 140 [Yucatan Peninsula, Mexico] [41].—Ortiz & Lalana, 2018: 112 [Cuba] [42].—Wetzer et al., 2018: 11, 12, Figure 5 [phylogenetic placement] [19].—Michaud et al., 2022: 16 [west coast of Florida] [43].—Nelson et al., 2022: 111, 119 [east coast of Florida] [33].

Remarks. In 1987, Kensley [2] erected Harrieta as a new monotypic genus for Exosphaeroma faxoni Richardson, 1905 and this has been followed in all subsequent papers, including those of a taxonomic nature (e.g.,[18]) as well as numerous faunal studies (e.g., [35,41]). The combination Exosphaeroma faxoni has not been used post-1955, except by Menzies & Glynn [23] who apparently forgot that the species was transferred to Cymodoce in [22]. The combination Cymodoce faxoni has only been used once after 1987, when Harrieta was erected, by Nelson et al. [33], who used both Cymodoce faxoni and Harrieta faxoni in their tables, but the use of the former combination was clearly a lapsus. Two additional species described in Exosphaeroma (E. antillense Richardson, 1912 [44], and E. barrerae Boone, 1918 [45]) were previously placed in synonymy with E. faxoni by Menzies & Kruczynski [27] but Kensley [2] refuted this. Both species are currently considered to be distinct from Harrieta faxoni but are listed as incertae sedis by Bruce [46] (as E. antillense) and Khalaji-Pirbalouty et al. [47] (as Cymodoce barrerae).

As part of an ongoing process of adding missing isopod taxa and relevant data to WoRMS [48], I recently discovered that E. faxoni was the type species of a long-overlooked genus name: Heteruropus Verhoeff, 1942. Verhoeff’s paper [3] contained eleven new generic or subgeneric new names, of which three (Europosphaera, Mexicosphaera, and Neosphaeroma) are unavailable due to his not designating a type species ([14], Article 13.3). Five additional names (Mexicosphaera, Nesosphaeroma, Pleosphaeroma, Tagrosphaeroma, and Ypsiloma) are available as the genera were monotypic but are currently considered junior subjective synonyms of other sphaeromatid genera. Three monotypic names are available and should be used as the accepted names for their respective genera: Buchnerillo, Lekanesphaera, and Heteruropus. The first two of these have long been used as the accepted names at the genus level but the last has not, probably because of Verhoeff’s [3] odd citation of the sole species therein as “Heteruropus m. (faxoni Rich.—Florida)” (where “m.” = mihi; i.e., described by the author as new). Harrison & Ellis [17], for example, did not include Heteruropus in their list of sphaeromatid genera.

Because Exosphaeroma faxoni is the type species of both Heteruropus Verhoeff, 1942 and Harrieta Kensley, 1987, and both names are available, Harrieta is a junior objective synonym of Heteruropus. Wetzer et al. [18] found that the sister taxon to H. faxoni was Paracilicaea mossambica Barnard, 1914 [49] but did not discuss if the two species should be considered congenetic; Paracilicaea Stebbing, 1910 [50] was, however, shown to be non-monophyletic in their analysis and is in further need of revision.

4. Discussion

Isopods are a highly diverse group of crustaceans with 666 accepted genera and 10,574 accepted species names ([48] as of 14 July 2023), with species occurring in terrestrial, freshwater, and marine habitats. Although the majority of accepted isopod names have been entered into WoRMS, there are still some taxonomic issues remaining, such as unrecognized synonymies and unreplaced homonyms. In some groups, taxon names long in synonymy have not yet been entered into the database. The ongoing curation of the isopod names entered into WoRMS, as well as the ongoing addition of new taxon names, newly discovered overlooked names, and combinations of genera and species not previously entered, will serve to continuously improve the quality of the data in this authoritative classification and catalogue of isopod names.