Acarnus tupiniquim, Ozga & Santos & Menegola, 2024

Ozga, Aline Vasum, Santos, George Garcia & Menegola, Carla, 2024, Taxonomic and geographic novelties of Acarnus (Porifera: Demospongiae) from the Brazilian coast, with description of two new species, Zootaxa 5523 (4), pp. 401-422 : 412-414

Acarnus tupiniquim sp. nov. Ozga & Menegola

( Fig. 6A–V ; Table 4 )

Material examined. Holotype: UFBA 2453 (Schizoholotype MUCIN 0151 ) Brazil, Bahia State, Maraú, Camamu Bay, Barra Grande , 13°55’08.8”S 38°59’59.3”W, VIII.2004, 16 m, coll. W. Andrade, Holme Dredge and Van Veen Grab, Det. A. Ozga & C. Menegola.

Diagnosis. Unique Acarnus species with tylostyles.

Description. Encrusting, thin to massive sponge, with sediments, algae fragments and shells both on its surface and interior, measuring approximately 1.3 x 2 cm. Surface hispid due to the presence of spicules and rough by the accumulation of sand grains. Firm consistency, however, easy to tear. Oscules and pores not visible. External and internal color beige after fixation ( Fig. 6A ).

Skeleton. Anisotropic reticulate skeleton ( Fig. 6B ) with ascending bundles of tylotes, around which single spicules are arranged irregularly, in many directions, resulting in triangular, rectangular or differently shaped meshes. Equinate cladotylotes protrude from the spicular bundles, directed towards the base or surface of the sponge. Monaxonic megascleres (styles, tylotes, cladotylotes and tylostyles) are abundant and randomly arranged from choanosome to ectosome, as well as toxas and chelae microscleres. Cladotylotes found in reduced numbers when compared to the tylotes.

Spicules. ( Fig. 6C–X ) Megascleres: styles ( Fig. 6C–E ), long and thick, straight and tapering from center to tip, with tapered end (370–653–900/ 7.5–10–15 µm). Tylotes ( Fig. 6F–H ) long and thin, straight with microspiny tyles (270–400–560/ 2.5–5.6–7.5 µm). Tylostyles ( Fig. 6I–M ), short and thin, with a smooth tyle at the tip and tapering from the center to the end. Hastate tip (127.5–155.8–177.5/ 2.5–3.5–5 µm). Cladotylotes I ( Fig. 6N, P, Q ), long and thick, with spiny shaft and spines curved towards the base, cladome well developed at one end and presenting four clads (127.5–184.8–232.5/ 5–5.8– 7.5 µm). Cladotylotes II ( Fig. 6O, R, S ), short and thin, with a spiny shaft and spines curved towards the base, a developed cladome with four clads at one end (65–80.5–100/ 2.5–2.8–5 µm). Microscleres: toxas I (accolada) ( Fig. 6T–U ), long and thin, center smooth and straight and slightly curved, with tapered ends (200–239.3–310/ 2–2.1–2.5 µm). Toxas II ( Fig. 6V–W ), short and thin, smooth and very curved in the central region and slightly curved at the tip with tapered ends (47.5–66.8–80/ 0.8–1.3–1.6 µm). Toxa III (oxhorn) absent. Palmate isochelae ( Fig. 6X ), small, with a well-developed tab (12.5–15.8–17.5 µm).

Ecology and bathymetry. An agglomeration of biodetrital debris (fragments of shells and carapaces, calcareous nodules, etc.) inside the sponge, at a depth of 16 m.

Distribution. Southwest Atlantic, Brazil. Recorded from Northeast Brazil on the southern coast of the Bahia State (Camamu Bay, Maraú, Barra Grande).

Etymology. The specific epithet is in homage to the Brazilian indigenous group Tupiniquins that belong to the Tupi nation and are also called tupinaquis, topinaquis and tupinanquins. The Municipality of Camamu originated from a Tupiniquim village that was transformed into a parish in 1561, after the establishment of a Jesuit mission. They were the indigenous group encountered by the Portuguese squadron of Pedro Álvares Cabral, on April 22, 1500. They currently inhabit indigenous lands in the municipality of Aracruz, in the north of Espírito Santo State, in Brazil.

Remarks. Concerning the spicule set, Acarnus tupiniquim sp. nov. belongs to the “ tortilis ” group because it has spinate cladotylotes and lacks acanthostyles. The material studied differs from all congeneric species in its internal morphological characters, especially for having a type of tylostyle so far undocumented for the genus. The redefinition of Acarnus was necessary here to inclusion of this new species. In Acarnidae , the presence of tylostyles were briefly mentioned in Zyzzya fulliginosa (Carter, 1879) and Cornulum virguliferum (Lèvi & Lévi, 1983) .

Specifically, when compared with Atlantic species ( Table 4 ), A. tupiniquim sp. nov. differs of A. nicoleae , with records from the Caribbean to Brazil (Rio de Janeiro, Rio Grande do Norte, Pernambuco and Espírito Santo), due to absence of acanthostyles and presence of smooth styles, although both species have identical external morphological characters such as the ability to accumulate sediments and fragments of calcareous algae and shells adhered to the surface and inside the body. The new species differs from A. innominatus , which also occurs from the Caribbean to Brazil (Rio Grande do Norte, Pernambuco, Alagoas and Bahia), in having spiny cladotylotes. Besides A. innominatus , besides hasving flat cladotylotes I, these have them are larger (230–300/ 6–12 µm) than in the new species (127.5–232/ 5–7.5 µm). But when compared to A. deweerdtae , with records in the south Caribbean region, the new species differs by the presence of a tylostyle and by having larger and more robust styles (370–900/ 7.5–15 µm vs. 400–566/ 5–6 µm, respectively). Acarnus tupiniquim sp. nov. differs of A. tortilis , with records in north Atlantic, Azores, Canarias and Madeira, due to absence of amphitylotes and presence of three toxa categories.

In comparison to endemic species of Brazil, the set of spicules of Acarnus tupiniquim sp. nov. is closest to A. toxeata (Bahia and Espírito Santo), because they have a single category of styles, two categories of cladotylotes (spinate) and isoquelae, but both differ in the size of the cladotylotes, larger in A. toxeata (I 250–395/ 3–9 and II 56–162/ 3 µm) than in the new species (I 127.5–232.5/ 5–7.5 and II 65–100/ 2.5–5 µm).

In comparison to other species known to Brazil, A. radovani (Pernambuco, Rio Grande do Norte and Rio de Janeiro States) due to absence of acanthostyles and presence of two cladotylotes categories. Meanwhile, it is set apart of A. microxeatus (Alagoas State) due to absence of acanthostyles and microxeas. Finally, Acarnus tupiniquim sp. nov. of Acarnus hooperi sp. nov. due to absence of acanthostyles and tylostyles.

Figures

FIGURE 6. Acarnus tupiniquim sp. nov. (Holotype UFBA 2453). A, preserved specimen; B, skeletal architecture; C, style; D and E, detail of the style; F, tylote; G and H, detail of the tylote; I and J, tylostyles; K, L and M, detail of the tylostyles; N, cladotylote I; O and P, detail of the cladotylote I; Q, cladotylote II; R and S, detail of the cladotylote II; T, toxa I; U, detail of the toxa I; V, toxa II; W, detail of the toxa II; X, palmate isochelae. Scales: A, 0.5 cm; B, 100 µm; C, 20 µm; D, E, F, 10 µm; G, H, 3 µm; I, J, 10 µm; K, L, M, 1 µm; N, 20 µm; O, P, 3 µm; Q, 20 µm; R, S, 3 µm; T, 50 µm; U, 1 µm; V, 10 µm; W, 1 µm; X, 2 µm.