Spirastrella mollis Verrill, 1907

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 : 28-29

publication ID	https://doi.org/ 10.11646/zootaxa.5031.1.1
publication LSID	lsid:zoobank.org:pub:CC3A59D1-E09E-407E-93F4-4796FD3D7C19
persistent identifier	https://treatment.plazi.org/id/110587B3-4D10-480D-FF53-F939486F32B6
treatment provided by	Plazi
scientific name	Spirastrella mollis Verrill, 1907
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Spirastrella mollis Verrill, 1907 View in CoL

Tables 6, 7; Figs. 21A–E View FIGURE 21 , 36D View FIGURE 36

Synonymy and references: Spirastrella mollis Verrill (1907: 344) , Rützler (1986: 122), Rützler et al. (2000: 234), Rützler et al. (2014: 38), Pérez et al. (2017: 12) and Van Soest (2017: 172); Spirastrella aff. mollis: Ugalde et al. (2015: 159) .

Type locality. Bermuda .

Material examined. CNPGG-2424, Isla Verde reef (19.1984°N, - 96.0686°W), 6 m depth, coll. Diana Ugalde, 28 August 2018 GoogleMaps .

Description. Encrusting habit with swelling veins in vivo that end in the oscules ( Fig. 36D View FIGURE 36 ). Surface smooth, fleshy, scattered oscules provided with an elevated membrane, 4–6 mm diameter. Orange-salmon or reddish color in vivo, and beige color in ethanol. Consistency is firm, easy to fall apart.

Skeleton. Brushes of spicules densely packed and perpendicular to the surface, with outward pointed ends, spirasters densely distributed through surface forming a cortex ( Figs. 21A–B View FIGURE 21 ).

Spicules. Megascleres: Tylostyles straight 280– 415 (54.6)–490/2.5–8.323 (2.9)–12 µm, mainly ovoid heads, also rounded present, 5.5– 10.6 (2.2)–14 µm, tips acerate to hastate, sometimes rounded ( Fig. 21C View FIGURE 21 ). Microscleres: Spirasters I bent once or twice, with conical and single strong rays ( Fig. 21D View FIGURE 21 – 1 View FIGURE 1 ), 36– 44.87 (4.4)–50 × 5– 6.7 (0.8)–9 µm, spirastes II bent once with conical rays ( Fig. 21D View FIGURE 21 – 2 View FIGURE 2 ), 13– 21.12 (4.3)–26.5 × 1.5– 2.7 (0.7)–5 µm, spiraster III bent once with bifid rays ( Fig. 21D View FIGURE 21 – 3 View FIGURE 3 , E) 5–7.1 (1.4) 9.5 × 1– 1.8 (0.3)–2.4 µm.

Distribution. Mexico ( Ugalde et al. 2015; De la Cruz-Francisco & Bandala-Pérez 2016; current records), Bermuda, Bahamas, and other Caribbean Sea countries ( Rützler et al. 2014).

Remarks. There are five valid species of Spirastrella for the Tropical Northwestern Atlantic (TNwA). Three of them have been recorded for the GoM: Spirastrella coccinea ( Duchassaing & Michelotti, 1864) , Spirastrella coccinopsis de Laubenfels, 1953 , and Spirastrella mollis Verrill, 1907 . Spirastrella mollis was recorded by Ugalde et al. (2015) in the Campeche Bank, identified as an affinity of the species, due to the differences in the spirasters morphology, in contrast with those described by Rützler et al. (2014). The present material corresponds to the description of S. mollis by Rützler, et al. (2014); the characters of our material are similar in color and morphology in vivo, also with the measurements and shape of the tylostyles and spirasters. Additionally, it was frequent to observe small spirasters in the transition to amphiasters (5–9.5 µm tick) according to the specimens recorded by Rützler et al. (2014). Thus, corroborating the presence of S. mollis in the GoM. On the other hand, S. mollis and S. hartmani are controversial species, possibly in synonymy. In the brief original description of Spirastrella mollis there are no spicule measurements (Verril 1907), and the type specimen has gone missing, complicating the comparison with the actual specimens. Consequently, Boury-Esnault et al. (1999) described Spirastrella hartmani as a new species, mainly by comparing the differences in the shape of the spirasters to S. mollis . However, Rützler et al. (2014) suggest that S. hartmani and S. mollis are the same species, considering the differences in the spicules’ measurements and shape due to normal variation between populations and the few specimens reviewed. Both species, S. mollis and S. hartmani are currently accepted ( van Soest et al. 2021). For these reasons, we suggest a revision of the Spirastrella spp. of the TNwA, including S. coccinopsis with a brief description. Spirastrella mollis has not been registered since its first sighting by de Laubenfels (1953).