Thesea Duchassaing & Michelotti, 1860

Horvath, Elizabeth Anne, 2019, A review of gorgonian coral species (Cnidaria, Octocorallia, Alcyonacea) held in the Santa Barbara Museum of Natural History research collection: focus on species from Scleraxonia, Holaxonia, Calcaxonia - Part III: Suborder Holaxonia continued, and suborder Calcaxonia, ZooKeys 860, pp. 183-306 : 225-226

Genus Thesea Duchassaing & Michelotti, 1860

Thesea = Acis (non Acis , Billberg, 1820, Lesson 1830) Duchassaing & Michelotti, 1860: 18, 19; 1864: 12-14. Kölliker 1865: 136. [ Thesea . = Acis (pars) Wright and Studer 1889: 56.

Acis Kükenthal, 1919: 836.

Thesea Duchassaing & Michelotti, 1860: 18, 19. Nutting 1912: 80. Kükenthal 1924: 153, 154. Deichmann 1936: 110-112. Bayer 1956: F206-F207; 1958: 50; 1981: 945.

non Thesea Nutting, 1910a: 50 {= Placogorgia }. Riess 1929: 401 [= Scleracis : see Deichmann, 1936: 111].

non Elasma (non E. Jaennicke, 1866); Studer (and Wright) 1887: 58.

non Elasmogorgia Wright & Studer, 1889: 132. Hickson 1905: 814. Nutting 1909: 717 (California = Thesea ). Thomson and Simpson 1909: 238. Nutting 1910a: 45. Thomson and Russell 1910: 159. Nutting 1912: 85. Kükenthal 1919: 752, 836; 1924 (pars): 148]. Thomson and Dean 1931: 199. Matsumoto and Ofwegen 2016: 4.

Evacis (nomen nudum) Verrill, 1912: 373, 377 [Des. Deichmann, 1936].

Euacis Aurivillius, 1931: 126.

Filigella Gray, 1868: 443. Kinoshita (pars) 1909: 1. Verrill 1912: 389. Kükenthal 1919: 762, 844. Aurivillius 1931: 126-129. Deichmann 1936: 147. Bayer 1956: F206. Muzik 1979: 142, 143; Matsumoto and Ofwegen 2016: 2, 16, 19.

non Filigella = Elasmogorgia Kinoshita, 1909: 1, 4, 5. Kükenthal 1924: 148.

Heterogorgia (pars) Verrill, 1868c: 413. Nutting 1910a: 87.

Type species.

Thesea exserta Duchassaing & Michelotti, 1860 (non Gorgonia exserta Ellis & Solander, 1786) = Thesea guadalupensis Duchassaing & Michelotti, 1864.

Diagnosis.

Colonies moderately threadlike, some (rare) sparsely branched in one plane; slightly flexible branches slender, long, each ascending to slightly expanded, stout, possibly truncated, distal branch tip; terminates with flattened arrow-head-like tip; proximal end, when free, also drawn into arrow-head (looking as distal end), or with small attachment disk; axis horny; coenenchyme thin. Calyces distinct, roughly placed alternately; low-domed with eight marginal teeth formed by simple converging spindles. Sclerites of coenenchyme in two layers: outer one containing large, spheroidal/oval or plate-like bodies, outer faces of which are commonly undulated, generating a wash-board appearance (key sclerite form for genus); inner layer including warted spindles of smaller diameter.

Remarks.

Kinoshita (1909) and Aurivillius (1931) considered the genus Filigella synonymous with Elasmogorgia . This synonymy was called into question by Matsumoto and Ofwegen (2016) in statements made regarding two distinct species. They stated that Filigella mitsukurii is actually Euplexaura mitsukurii and that there is only one species in the genus Elasmogorgia , that being Elasmogorgia filiformis Wright & Studer, 1889 (closely resembling a species in the genus Astrogorgia Verrill, 1868); in actuality, there now are three accepted species in this genus, listed accordingly by Cordeiro et al. (2019) in the WoRMS Database. Considering the characteristics of the two genera ( Euplexaura Verrill, 1869 and Elasmogorgia ), neither E. mitsukurii or E. filiformis belong in the genus Thesea ; thus Elasmogorgia is not synonymous with Thesea . However, Matsumoto and Ofwegen (2016) did state that the genus Filigella is a synonym of Thesea . The basis for this might be the fact that the genus descriptions given by Bayer (1956 a) for Thesea and Filigella overlap, in part; this would explain the suggestion of synonymy between the two genera made by Bayer in 1958. Bayer (1958) synonymized the two genera Filigella Gray and Elasmogorgia Wright and Studer with the West Atlantic genus Thesea Duchassaing & Michellotti, and transferred the genus to the family Plexauridae from the family Paramuriceidae (latter no longer a currently recognized taxon). Bayer (1981) then stated that Filigella was a synonym of Thesea ; based on the recent work of Matsumoto and Ofwegen (2016), Elasmogorgia must be removed from Bayer’s 1958 synonymy, while Filigella 's synonymy might be retained. According to Utinomi (1961) however, the coenenchyme of Filigella is thinner and less distinctly displays the two layers seen in most plexaurids; as well, anthocodial armature is more powerful so as to form an operculum, typical of the group formerly known as the paramuriceids. Based on this, he considered it better to retain the genus name Filigella than to unite it with the plexaurid genus Thesea . Muzik (1979) also did not synonymize Thesea with Filigella ; her rationale was that Filigella had a distinct collaret (having something more like a true operculum), along with numerous scales forming the tentacle backs. While Filigella was considered to be similar to Thesea , Thesea was stated to have "bulky boots" (Muzik, 1979: 143) forming its ( collaret’s) points. She went on to surmise that, "depending on the importance of anthocodial armature, these three genera ( Thesea , Filigella , along with Muricella ) may remain distinct or one day be merged into one genus." The NMNH did not use/recognize Filigella during times when author visited and worked in the collection; Thesea was the genus designation used. From examinations of specimens at NMNH, etc., noting specimen identification while also considering the synonymy discussion given here, Thesea and Filigella may or may not be synonymous; the genus Thesea is used here for colonies from California (and Mexican) waters. Elasmogorgia (and its species, including E. filiformis ) is not considered, based on the recent work of Matsumoto and Ofwegen (2016). Cordeiro et al. (2019), in the WoRMS Database, indicated the genus Thesea as having accepted status, and they list some twenty-eight species within the genus; however, neither Thesea [non Elasmogorgia ] filiformis (Nutting, 1909) or Thesea variabilis (Studer, 1894) are included in that listing.