Samus anonymus Gray, 1867a

Bettcher, Larissa, Fernandez, Julio C. C., Gastaldi, Marianela, Bispo, André, Leal, Camille V., Leite, Dora, Avelino-Alves, Dhara, Clerier, Pedro H. B., Rezende, Dafinny, Gulart, Clara M. R., Pinheiro, Ulisses & Hajdu, Eduardo, 2023, Checklist, diversity descriptors and selected descriptions of a highly diverse intertidal sponge (Porifera) assemblage at Costa do Descobrimento (Bahia, Brazil), Zootaxa 5277 (3), pp. 443-489 : 475-476

Samus anonymus Gray, 1867a

( Tab.1–2, 11; Fig. 14A–G )

Studied material. MNRJ 22223 , P.M.M. Coroa Alta (16°13.200′ S, 38°57.038′ W, Santa Cruz Cabrália, BA, Brazil), intertidal, coll. Hajdu, E. & Avelino, D., 22 nd April 2019 .

Description. Endolithic. Surface, consistency and color (in vivo) not recorded; yellowish-beige in fixative ( Tab. 11; Figs. 14A–B ).

Skeleton. Ectosome not distinct from the choanosome. Choanosome with scattered megascleres and relatively abundant microscleres. Compact appearance, with a few rounded channels (up to 170 µm in diameter) and points of attachment to the substrate. Presence of several large flattened spaces adjacent to the substrate ( Figs. 14C–F ).

Spicules. Megascleres ( Tab. 11; Figs. 14C–E ): smooth short-shafted amphitriaenes in the shape of amphiproor amphiplagiotriaenes and symmetrical amphitrichotriaenes, with dichotomous or trichotomous cladi, but both arrangements can be present in a same spicule; total length, 40–81.3–120 µm (n=8), rhabdome, 10–20.9–23 x 2.5–8.2–18 µm (n=8), protocladi, 5–14.5–38 µm (n=10), and deuterocladi, 20–24.3–30 µm (n= 9). Microscleres ( Tab. 11; Fig. 14F ): sigmaspires, 10–10.8–13 µm.

Distribution. Previously Bermuda ( de Laubenfels 1950), the Greater Caribbean [Florida ( de Laubenfels 1936); Western Carib. ( Macintyre et al. 1982; Ŗtzler et al. 2014); Southwestern Carib. ( Wintermann-Kilian & Kilian 1984; Łukowiak 2016)], Gulf of Guinea ( Lévi 1959), Mediterranean ( Vacelet 1976; Pulitzer-Finali 1983; Voultsiadou 2005), Southwestern Atlantic [off Salvador, BA, Brazil ( Sollas, 1888)]. New record—Costa do Descobrimento, BA, Brazil.

Ecology. The specimen was growing in calcareous substrate (coral piece).

Remarks. The species was found unexpectedly while sectioning a piece of coral. Despite the sponge seemingly inhabiting a canal leading to the outer medium, it could not be spotted after careful examination of the whole substrate with light-microscopy (stereoscope). Light-microscopy did not allow the verification of whether sigmaspires of the examined material carry a lot of or a few spines. However, the spiculation observed fits well in S. anonymu s (see revision in van Soest & Hooper 2002), despite the smaller dimensions of the cladi and rhabdomes of the amphitriaenes ( Tab. 11).

The various records of S. anonymus from all over the world (the Indo-Pacific—Siri Lanka, Seychelles, Singapore and Palau Islands; Atlantic—Florida, Colombia, Curaçao and West Africa; and the Mediterranean— several localities) describe similar spicule sizes and forms, but such records are suspect from a genetic point of view, since populations are widely separated ( van Soest & Hooper 2002). Currently, the World Porifera Database ( de Voogd et al. 2022) only accepts as likely conspecific Atlanto-Mediterranean records of this species, but in our opinion this Amphi-Atlantic distribution already demands corroboration from additional data sources. The species was originally based on a record from Bahia illustrated by Bowerbank (1864), subsequently used by Gray (1867) to erect the taxon.As already pointed out in van Soest & Hooper (2002), several subsequent records of the species from widely separated areas in every Tropical Ocean need genetic corroboration of their alleged conspecificity. Given the species’ cryptic habit (i.e., endolithic / excavating— van Soest & Hooper 2002), this will demand a concerted effort to gather a minimum number of samples of reasonable dimensions. Ours, a topotypical specimen, unfortunately, is too small to kickstart this process.

This ocean basin classification of identification likelihood has been a guiding principle in the World Porifera Database, but care should be exercised not to mask invasive/cryptogenic species, as well as potential conservative taxonomy. The latter fails to recognize species complexes where the character sets available for study do not receive all the attention needed to properly distinguish these species, or alternative sources of data such as DNA are disregarded due to an incorrect judgment of their need, to technical or resource limitations. Ŗtzler et al. (2014) have reported microspined amphitriaenes in Belizean materials identified as S. anonymus , besides the normal smooth ones. The latter authors argued that the microspined forms are possibly developmental stages of the mature forms, despite recognizing that these spined forms had not been mentioned in the previous taxonomic literature on the species, which included the Systema Porifera review of its type material by van Soest & Hooper (2002). Might Ŗtzler et al. ’s (2014) material belong to an unknown species of Samus ? These suspicions further support the need for an integrative review of the species as argued for above.

Figures

FIGURE 14. Samus anonymus Gray, 1867a, MNRJ 22223: A–B, substrate where the specimen was found; B, gallery where arrow is pointing in A. Skeleton and spicules: C, transverse sections showing amphitriaenes beneath the surface and scattered throughout the choanosomal region; D, smaller amphitriaenes—arrows pointing to them; E, channels in the choanosome as well as bordering it and F, sigmaspires bordering a channel.