Iotrochota arenosa Rützler, Maldonado, Piantoni & Riesgo, 2007

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 : 55-56

Iotrochota arenosa Rützler, Maldonado, Piantoni & Riesgo, 2007

Tables 6, 7; Figs. 50A–D , 58E

Synonymy and references: Iotrochota arenosa Rützler et al. (2007: 179) , and Castello-Branco & Menegola (2014: 2); Iotrochota cf. arenosa: Pérez et al. (2017: 11) .

Type locality. Belize .

Material examined. CNPGG-2422, Isla Verde reef (19.19844°N, 96.06863°W), 7.3 m depth, coll. Diana Ugal- de, 28 August 2018 ; CNPGG-2452, Isla Verde reef (19.19844°N, 96.06863°W), 3.6 m depth, coll. Diana Ugalde, 31 August 2018 .

Description. Thickly encrusting habit ( Fig. 58E ); the larger specimen’s size 7 ×7 × 1 cm. Surface microconulose and without visible pores. Oscules small (up to 2 mm in diameter), flush to the surface, and scattered. Purplish dark color in vivo and brownish dark preserved in ethanol. The consistency is flexible and slightly friable.

Skeleton. Reticulation of multispicular tracts of styles and strongyles (multispicular, 30–50 µm thick; Fig. 50A ). Some spicules scattered throughout the reticulation. Some thin strongyles paratangential at the surface ( Fig.50B ). Birotules scattered throughout the skeleton. No visible sand grains.

Spicules. Megascleres: Styles stout, curved, and smooth ( Fig. 50C – 3 ); 134– 155.6 (10.7)–170/5–8.2 (1.8)–11 µm. Strongyles I straight and smooth ( Fig. 50C – 1 ); 210– 218.5 (7.4)–230/5–6 (0.8)–7.5 µm. Strongyles II very similar to the previous category but slightly longer and thinner ( Fig. 50C – 2 ); 230– 241 (7.6)–260/3–4.1 (0.8)–6 µm. Microscleres: Birotule abundant and small ( Fig. 50D ); 9.5– 11.1 (1.1)–12 µm in length.

Distribution. Mexico (current records), Belize ( Rützler et al. 2007b), Brazil ( Castello-Branco & Menegola 2014).

Remarks. I. arenosa has only been recorded in Belize ( Rützler et al. 2007b) and southeastern Brazil (Castello- Branco & Menegola 2014). Thus, our study presents the first record for the GoM. The present material was assigned to I. arenosa owing to three main features: 1) embedded sediment grains are absent in our material, 2) purplish brown, almost black color when alive in the type species, and 3) spiculation similar to that of the type material ( Table 3). According to Castello-Branco & Menegola (2014) I. arenosa from Brazil does not possess sand grains and has much larger measurements in all spicules. The taxonomic significance of this variation must be determined before changing the diagnosis of the species, but this was beyond the scope of our study.

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 3. Agelas conifera (Schmidt, 1870) (CNPGG-2364), skeleton and spicules: A. transversal section of the skeleton; B. detail of the ectosomal region; C. detail of the choanosomal region; D. verticillated acanthostyles. Scale bars: A = 1000 µm; B–C = 200 µm; D = 100 µm.

FIGURE 50. Iotrochota arenosa Rützler, Maldonado, Piantoni & Riesgo, 2007 (CNPGG-2422), skeleton and spicules: A. transversal section of the skeleton; B. ectosomal region with brushes of strongyles II (slender strongyles); C. 1—strongyles I, 2— strongyles II, 3— styles; D. birotules. Scale bars: A = 100 µm; B = 20 µm; C = 25 µm; D = 10 µm.

FIGURE 58. In situ photographs of species analyzed in the present study: A. Acarnus innominatus Gray, 1867 (CNPGG-2393); B. Monanchora arbuscula (Duchassaing & Michelotti, 1864) (CNPGG-2204); C. Strongylacidon bermuda (de Laubenfels, 1950) (CNPGG-2170); D. Desmapsamma anchorata (Carter, 1882) (CNPGG-2443); E. Iotrochota arenosa Rützler, Maldonado, Piantoni & Riesgo, 2007 (CNPGG-2422); F. Mycale (Mycale) laevis (Carter, 1882) (CNPGG-2273); F. Mycale (Arenochalina) laxissima (Duchassaing & Michelotti, 1864) (CNPGG-2267); H. Polymastia tenax Pulitzer-Finali, 1986 (CNPGG-22587); I. Scopalina ruetzleri (Wiedenmayer, 1977) (CNPGG-2183); J. Svenzea cristinae Alvarez, van Soest & Rützler, 2002 (CNPGG- 2474); K. Svenzea flava (Lehnert & van Soest, 1999) (CNPGG-2288); L. Svenzea tubulosa (Alcolado & Gotera, 1986) (CN- PGG-2272), surface detail zoomed in (arrow indicates white channels in the choanosomal region). Scale bars, A–L = 1 cm.