Tethya diploderma Schmidt, 1870

Ugalde, Diana, Fernandez, Julio C. C., Gómez, Patricia, Lôbo-Hajdu, Gisele & Simões, Nuno, 2021, An update on the diversity of marine sponges in the southern Gulf of Mexico coral reefs, Zootaxa 5031 (1), pp. 1-112 : 71-72

Tethya diploderma Schmidt, 1870

Tables 5, 6, 7; Figs. 65A–F , 70I

Synonymy: Tethya diploderma Schmidt, (1870: 52) , de Laubenfels (1953:545), Pulitzer-Finali (1986: 98).

Type locality. Antilles , St. Croix .

Material examined. CNPGG-2191, Cayo Arcas reef (20.2051°N, 91.9630°W), 0.5 m depth, coll. Diana Ugal- de, 19 August 2018 .

Description. Hemispherical habit ( Fig. 70I ); size 1.8 × 0.8 cm. The surface has round tubercles and is microhispid as well, scattered foreign detritus attached. The oscules are not visible. Yellow color in vivo, beige preserved in ethanol. The consistency is firm and slightly compressible.

Skeleton. Cortex well developed 850–1250 µm thick, formed by abundant megasters and micrasters of the tylaster type, with foreign detritus also incorporated here ( Figs. 65A–B ). The choanosomal skeleton is formed by ascending tracts of strongyloxeas, 175–250 µm thick in a radial pattern. These bundles are crossing the cortex in some areas, making the strongyloxeas protrude outside the surface.

Spicules. Megascleres. Principal strongyloxeas straight, and hastate ends ( Fig. 65C – 1 ), 750– 1087.3 (187.2)– 1350/11– 15.3 (2.8)–19 µm, accessory strongyloxeas ( Fig. 65C – 2 ), straight and hastate ends, 280– 362 (39.3.2)– 430/4.5– 6.5 (1.8)–10.5 µm. Microscleres. Megasters are spherasters ( Fig. 65D ), with smooth rays and a thick center, overall diameter 30– 41 (10.6)–65 µm. Micrasters are two types: strongylasters ( Fig. 65E ), with microspined ends and varied number of rays, 9– 11.8 (1.8)–15 µm in diameter; and oxyaster with straight rays ( Fig. 65F ), sometimes with microspined tips, 5– 8.9 (2.8)–14 µm in diameter.

Distribution. Mexico (current records), US (Florida, de Laubenfels 1953), Jamaica, Puerto Rico ( Pulitzer-Finali 1986).

Remarks. The specimen examined is consistent with T. diploderma in the external morphology, skeleton, and spicules as recorded by de Laubenfels (1953), and complemented by Ribeiro & Muricy (2011). Schmidt’s original brief description only mentions the presence of needles as part of the spiculation, that must correspond to megascleres (without measurements), and two categories of asters, which must correspond to the spheraster type (>30 µm), and tylasters with 6–9 swollen tip rays (8.5 µm). On the other hand, the spicular set of the species has been completed by Ribeiro & Muricy (2011) adding the strongylaster, tylaster and oxiaster types when re-examining an original specimen from Schmidt ( Table 5). Apparently, microscleres (megasters and micrasters) are the main differences among Tethya species (Sará 2002, Ribeiro & Muricy 2011). Apart from T. diploderma , four species of Tethya had been reported in the Caribbean Sea: T. seychellensis ( Wright 1881) , T. aurantium ( Pallas, 1766) , T. maza Selenka 1879 , and T. actinia de Laubenfels 1950 . The first two species, T. seychellensis and T. aurantium originally from the Indian Ocean and the Mediterranean Sea, are doubtful records for the TNwA. It is unlikely that gene flow can occur between amphi-Atlantic populations given the low dispersal capabilities of sponge larvae ( Klautau et al. 1999). On the other hand, T. maza differs from the present material of T. diploderma by having larger megascleres I (up to 1868 × 32 µm), larger megasters (up to 100 µm) with bifurcated rays, diameter of strongylasters twice as large (30 µm), and a thicker cortex (up to 650 µm). Likewise, T. actinia is distinguished by its cortex over 1 mm thick, strongyloxeas over 2000 µm long, and oxiasters with bifurcated rays.

For the moment, we must rely on Ribeiro & Muricy´s (2011) reexamination of Schmidt´s original specimen of T. diploderma , where they could find only micrasters. On the other hand, de Laubenfels (1953) also reported spicule measurements as well as morphological traits such as the 1 mm thick cortex ( Table 5). Considerable intraspecific variability is reported for TNwA species of Tethya ( Table 5), rendering it difficult to identify new materials confidently. Moreover, information is frequently incomplete on type materials (e.g. T. diploderma ), thus compounding the problem. We advocate that only a large, integrative assessment of Tethya spp from several localities in the TNwA will settle species boundaries more confidently.

Figures

FIGURE 1. Map of sampling localities explored in this study in the southern Gulf of Mexico. The localities include 16 coral reefs from Veracruz to Campeche Bank and one station in the Chelem lagoon in Yucatan Peninsula.

FIGURE 2. Agelas clathrodes (Schmidt, 1870) (CNPGG-2297), skeleton and spicules:A. transversal section of the skeleton; B. detail of the ectosomal region, upper side; C. verticillated acanthostyles. Scale bars: A = 500 µm; B = 100 µm; C = 50 µm.

FIGURE 65. Tethya diploderma Schmidt, 1870 (CNPGG-2191), skeleton and spicules: A. transversal section of the skeleton, radial tracts of megascleres (strongyloxeas) and several sand grains in choanosomal region; B. detail of the ectosomal region with a layer of aster microscleres and part of the tracts of strongyloxeas; C. strongyloxeas, 1—large category and 2—small category; D. spherasters; E. strongylasters; F. oxyaster. Scale bars: A = 500 µm; B = 250 µm; C = 100 µm; D = 25 µm; E–F = 5 µm.

FIGURE 70. In situ photographs of species analyzed in the present study: A. Svenzea tubulosa (Alcolado & Gotera, 1986), B. Svenzea zeai (Alvarez, van Soest & Rützler, 1998) (CNPGG-2284); C. Hymeniacidon caerulea Pulitzer-Finali, 1986 (CNPGG- 2425); D. Topsentia ophiraphidites (de Laubenfels, 1934) (CNPGG-2185); E. Topsentia ophiraphidites (de Laubenfels, 1934) (CNPGG-2262); F. Topsentia ophiraphidites (de Laubenfels, 1934) (CNPGG-2415); G. Tectitethya crypta de Laubenfels, 1949 (CNPGG-2176); H. Tectitethya macrostella Sarà & Bavestrello, 1996 (CNPGG-2277); I. Tethya diploderma Schmidt, 1870 (CNPGG-2191); J. Timea stenosclera Hechtel, 1969 (CNPGG-2275); K. Timea stenosclera Hechtel, 1969 (CNPGG-2358), surface detail zoomed in (arrow indicates a specimen of Chalinula aff. molitba); L. Stellettinopsis megastylifera (Wintermann- Kilian & Kilian, 1984) (CNPGG-2446); M. Geodia gibberosa Lamarck, 1815 (CNPGG-2291); N. Geodia neptuni (Sollas, 1886) (CNPGG-2439). Scale bars, A–N = 1 cm.