Placospongia beatrizae Sandes & Moraes & Muricy 2024, sp. nov.
Creators: name: Sandes, Joana
name: Moraes, Fernando
name: Muricy, Guilherme
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Porifera
Demospongiae
Clionaida
Placospongiidae
Placospongia
Placospongia beatrizae

description: Placospongia beatrizae sp. nov. Sandes, Moraes & Muricyurn:lsid:zoobank.org:act: 89774C02-D936-4CB6-936D-CD7EA50D6071
(Figs. 4 and 13–14; Tables 2–3, 6 and 7)
Synonyms
Placospongia melobesioides sensu González-Farías (1989); Mothes et al. 2006: 670 (non Placospongia melobesioides Gray, 1867).
Placospongia sp. 2 sensu van Soest 2009: 11.
Type material. Holotype: MNRJ 20307, Buraco da Raquel, Fernando de Noronha Archipelago, Pernambuco State, Brazil (03º50’2.760”S, 32º23’51.720”W), 0.5–2.0 m depth, colls. Cristiana Castello-Branco & Camille Leal, 21 April 2016. Paratype: MNRJ 20304, Buraco da Raquel, Fernando de Noronha Archipelago, Pernambuco State, Brazil (03º50’2.760”S, 32º23’51.720”W), 0.5–2.0 m depth, colls. André Bispo & Sula Salani, 21 April 2016.
Etymology. The name beatrizae is given in honour of Dr. Beatriz Mothes, who discovered this species in Northern Brazil (Mothes et al. 2006 as P. melobesioides), for her great contribution to sponge taxonomy in Brazil.
Diagnosis. Placospongia thinly encrusting, with light brown to reddish brown color. Megascleres are two categories of tylostyles and microscleres are mature selenasters, micro-spheroxyasters, some of which are variable in shape and similar to micro-spirasters and acanthomicrorhabds.
Description (Fig. 13a–b). Shape thinly encrusting, with approximately 2.0– 3.5 cm x 1–2 cm x 1–2 mm (length x width x thickness). The surface is smooth, divided into cortical plates of polygonal shape, separated by grooves and ridges with circular openings. The holotype has circular to oval oscules of 1–3 mm in diameter, visible only in vivo (Fig. 13b). The external color in vivo is light brown (Fig. 13a) to reddish-brown (Fig. 13b). In ethanol, the external color is dark brown, the grooves are light brown and the internal color is cream. The consistency is firm.
Skeleton (Fig. 13c–d). The cortex measures 500–800 µm thick and is densely packed with selenasters (Fig. 13c). Micro-spheroxyasters are scattered through the outer layer of the cortex. Small tylostyles occur in the cortical region together with micro-spheroxyasters, through the aquiferous openings, which are devoid of selenasters (Fig. 13d). The choanosomal skeleton is formed by tylostyle tracts 150–310 µm thick that run obliquely or perpendicularly from the substrate to the cortex (Fig. 13c). Mature selenasters and immature selenasters are also scattered in the choanosome among the bundles of tylostyle. The micro-spheroxyasters occur abundantly in the choanosome, frequently in groups, lining the choanosomal openings. At the base there is a further layer of selenasters 120–310 µm thick (Fig. 13c).
Megascleres (Fig. 14a–c; Tab 6). Two categories of tylostyles. Tylostyles I are large, choanosomal, with blunt ends and rounded tyle: 570–726–940 / 6–9–13 µm, tyle 7–12–15 µm in width (Fig. 14a–b). Tylostyles II are small, cortical, with blunt or mucronate ends and rounded tyle: 230–329–470 / 2–5–8 µm, tyle 3–7–10 µm wide (Fig. 14c).
Microscleres (Fig. 14d–k; Tab. 6). Mature selenasters are circular to oval, with all spines fused, forming irregular or polygonal plates: total size 32–55–88 / 20–54–73 µm, hilum 7–14 µm in diameter (Fig. 14d). Four types of immature selenasters: (I) straight, slender, rugose and spiny, with spines scattered throughout the shaft: 12–17–20 / 2–5–8 µm (Fig. 14e); (II) elongate, stout, straight or slightly bent axis densely spined, with spines short and clustered: 19–20–22 / 9–10–11 µm (n=4) (Fig. 14f); (III) elongate, stout, with large and numerous spines: 22–25–28 / 12–15–15 µm (Fig. 14g); (IV) oval, stout, with spines very closely set, but still recognizable in their individuality: 32–36–40 / 22–25–28 µm (Fig. 14h). Micro-spheroxyasters are small, with smooth rays (Fig. 14i), variable in shape: some have a spiral axis, similar to micro-spirasters (Fig. 14j), and others have an elongated center, similar to acanthomicrorhabds (Fig. 14k): 1–2–4 µm in diameter.
Habitat. In Fernando de Noronha Archipelago, this species occurs under boulders in tide pools, 0.5–2.0 m depth (present study). The material from Amapá State described by Mothes et al. (2006) was dredged from 76 m depth on a sandy/detritic bottom.
Geographical distribution (Fig. 4; Tab. 2). Gulf of Mexico (González-Farías 1989 as Placospongia melobesioides). Brazil: Amapá State, Northern Brazil (Mothes et al. 2006 as Placospongia melobesioides) and Fernando de Noronha Archipelago, Pernambuco State, Northeastern Brazil (present study).
Taxonomic remarks. Placospongia beatrizae sp. nov. is defined by the combination of two categories of tylostyles, round to oval mature selenasters, and micro-spheroxyasters variable in shape, some being similar to micro-spirasters and others similar to acanthomicrorhabds. Spirasters and spherasters are absent.
The new specimens from Fernando de Noronha share the same spicule categories with those from Amapá State, Northern Brazil (Mothes et al. 2006 as P. melobesioide s) and Gulf of Mexico (González-Farías 1989 as P. melobesioide s) (Tab. 6). Although Mothes et al. (2006) considered the micro-spirasters as an immature stage of selenasters, their shape, size and position in the skeleton indicate that the micro-spirasters are variations of the micro-spheroxyasters, as in the new species. The sizes of most spicule types are also similar in both populations, but there is some uncertainty about the size of the selenasters of the Amapá specimen. In the text of the description, Mothes et al. (2006) stated that the selenasters measure 70–90–111 / 26–36–48 µm, but the scale bar in their Fig. 15 (op. cit., p. 672) indicated sizes between 46–52–57 / 28–41–46 µm, more similar to those of specimens from Fernando de Noronha Archipelago (Tab. 6). Although the real size of the selenasters from the Amapá specimen of Mothes et al. (2006) remains to be verified, we consider that it is cospecific with the specimens from Fernando de Noronha Archipelago herein described as a new species P. beatrizae sp. nov. (Tab. 7).
Placospongia melobesioides sensu stricto was first described from Borneo (Pacific Ocean) and it differs from the new species by its variable color (but mainly dark brown to purple), often branching shape, large size (up to more than 50 cm wide), and by the presence of spherasters, although these spicules are rare and could be absent in most specimens (Gray 1867; Becking 2013). In addition, the smaller tylostyles of P. melobesioides often have acerate ends, and its micro-spheroxyasters (called ‘spherules’ by Becking 2013) are uniform and do not show the variations to micro-spirasters or to acanthomicrorhabds seen in the new species (Tab. 3; Becking 2013).
Van Soest (2009) first proposed that P. melobesioides sensu Mothes et al. (2006) could be an undescribed species, which he named Placospongia sp. 2, due to the absence of spherasters, but supposed that P. melobesioides sensu González-Farías (1989) from the Gulf of Mexico could be P. cristata, despite the absence of spherasters. David-Colón et al. (2023) argued that the spherasters could be lost in transverse sections of some specimens for being too superficial, and considered these records tentatively as a synonym of P. cristata. However, our re-examination of the holotype of P. cristata showed that its spherasters are abundant and occur in both the ectosome and choanosome, being thus unlikely that they could be lost during sectioning. Thus, we also consider that P. melobesioides sensu González-Farías (1989) from the Gulf of Mexico is cospecific with P. beatrizae sp. nov. (Tab. 7).
Placospongia beatrizae sp. nov. and Placospongia cristata are very similar, sharing the presence of two categories of tylostyles, rounded mature selenasters, and presence of micro-spheroxyasters. They differ mainly by the absence of spherasters in the new species. In addition, the tylostyles and selenasters of the new species attain larger sizes, and the shape of immature selenasters and micro-spheroxyasters is more variable in the new species than in P. cristata (Tab. 3).
description: Published as part of Sandes, Joana, Moraes, Fernando & Muricy, Guilherme, 2024, Taxonomy of Placospongia Gray, 1867 from Northern and Northeastern Brazil, with description of two new species (Porifera: Demospongiae: Clionaida), pp. 495-525 in Zootaxa 5405 (4) on pages 517-520, DOI: 10.11646/zootaxa.5405.4.2, http://zenodo.org/record/10603692