A new species of Acarnus Gray, 1867 (Porifera, Demospongiae, Acarnidae) from NE Brazil Author Nascimento, Elielton 0000-0002-1260-3197 Departamento de Zoologia, Universidade Federal de Pernambuco, Recife, Brazil biologoefn@gmail.com Author Pinheiro, Ulisses Departamento de Zoologia, Universidade Federal de Pernambuco, Recife, Brazil text Zootaxa 2023 2023-05-23 5293 3 521 540 http://dx.doi.org/10.11646/zootaxa.5293.3.5 journal article 10.11646/zootaxa.5293.3.5 1175-5326 7961435 7A0F8C73-B94D-4FAE-A0D9-FFC3D86104E8 Acarnus innominatus Gray, 1867 ( Figures 6–7 , Table 4 ) Acarnus innominatus Moraes, 2011: 121 . Ugalde et al. 2021: 52 . Fig. 46 Examined Material. UFPEPOR 4329— Recife da Sereia ( 09°33’56”S 035º38’42”W , Alagoas State , Brazil ), 2 February 2010 , Col. Correia, M. D. UFPEPOR 4330— Recife da Sereia ( 09°33’56’’S 035º38’42’’W , Alagoas State , Brazil ), 2 February 2011 , Col. Correia, M. D. UFPEPOR 4331— Recife de Guaxuma ( 09º35’26”S 035º39’55”W , Maceió , Alagoas State , Brazil ) 27 March 2009 ; Col. Correia, M. D. UFPEPOR 4335— Recife de Jatiúca ( 9°39’16.8”S 35°41’51.6”W , Maceió , Alagoas State , Brazil ), 18 January 2011 . Col. Correia, M. D. Description ( Fig. 6A ). Thickly encrusting sponge, largest specimen (UFPEPOR 4335) with dimensions 6 x 4.5 x 1 cm (length x width x thickness). The surface is microhispid with spicules protruding externally and with subdermal gaps. Fragile and easy to break consistency. Color is beige in alcohol. Skeleton ( Fig. 6B ). Ectosome is formed by paratangential tylotes arranged tangentially to the surface, with cladotylotes in tufts. The choanosomal skeleton consists of a reticulation of multispicular tracts of styles, echinated by cladotylotes particularly at nodes, and, microscleres scattered in the choanosome. Spicules ( Fig. 7 ). (UFPEPOR 4335) Tylotes, terminally microspined (225– 252.9 –275/ 3– 3.5 –6 μm). Style (387– 422.5 –475/ 6– 18.2 –26 μm). Cladotylotes I, larger, smooth and straight to lightly curved shaft, well-defined rounded tyle base and cladome with long spines, length (237– 275.4 –300 μm), shaft width (6– 10.7 –13 μm), cladome width (22– 41.6 –32 μm). Cladotylotes II, smaller, shaft with recurved spines, rounded basal tyle (flattened), length (112– 125.5 –145 μm), shaft width (3– 3.8 –6 μm), cladome width (10– 13.5 –20 μm). Palmate isochelae, 13– 15.1 –20 μm. Toxas I, accolada (225– 358.3 –575 μm); Toxas II, thin, deeply curved, (112– 148.5 –212 μm); Toxas III, oxhorn (26– 45.7 –68 μm). Distribution. Brazil : Fernando de Noronha and Atol das Rocas Island ( MORAES et al, 2003 ; MORAES, 2011 ); Alagoas State (present study). Floridan ( LAUBENFELS, 1936 ). Floridian; Greater Antilles ( PULITZER-FINALI, 1986 ). Southern Caribbean ( VAN SOEST, 1984 ). Southern Gulf of Mexico ( UGALDE et al, 2021 ). Southwestern Caribbean ( ZEA, 1987 ). FIGURE 6. Acarnus innominatus Gray, 1867 (UFPE 4279). A, Preserved specimen; B, thick section showing the ectosome and choanosome. Scale, A, 1 cm; B, 400 µm. FIGURE 7. Acarnus innominatus Gray, 1867 (UFPE 4279). A, Style. B, Tylote. C, Detail of Style. D, Detail of tylote. E, Cladotylote I. F,F’ and F” growth forms of Cladotylote I. G, Cladotylote II. H, detail of the spined shaft of cladotylote II. I, Oxhorn toxa. J, Thin deeply curved toxa. K, Accolada toxa. L, Isochelae. Scale: A, B, E, G, 50 μm; C, D, F, F’, F”, H, L, 10 μm G, I, J, K, 20 μm. TABLE 4. Comparative morphological and spicule dimensions, and distribution data for valid published species in the Acarnus “ innominatus ” group of species. Values are in micrometers (µm), expressed as minimum–maximum or minimum– average –maximum length/width. References are numbered in parentheses and listed at the bottom of the table.

Species	Form of growth	Spicules	Occurrence/ Depth
Cladotylote	Megascleres others	Toxa (I—Oxhorn; II—Thin	Isochelae
(t: tylote; s: styles)	deep-curved; III—Accolada)
A. claudei van Soest,	Massive, consolidat-	I—160–230/8	t: 130–230/ 3–4	I—50–200/3–5	11–18	South Africa: Cape
Hooper & Hiemstra,	ing calcareous algae.	II—80–110/ 2	s: 175–400/ 6–20	II—50–140	Town, Mossel Bay and
19911	III—200–250	Pt. Elisabeth.
A. erithacus de	Massive, cushion-	I—180–610/5–	t: 160–420/2.5–7.5	I—230–650	10–15	Gulf of California/
Laubenfels, 19272	shaped or vase-	25.	s: 230–850/7.5–50	II—100–250	36–122 m
shaped	Cladome 12.5–90.	III—35–140 (accolada)
II—65–180/2.5–5. cladome	IV—25–100 (accolada)
5–20
A. innominatus Gray,	Thick incrusting	I—233–267.4–299/ 8.1–9.5–	t: 137– 268.4 –313/3.3–	I—61– 90.7 –123/ 4.7– 7.4 –	10– 14 –18	South Africa, Colombia,
18673	10.9	3.8–4.7	9.5	Dominican republic,
II—133–138/4.7	s: 404– 431.8 –461/10–	II—43– 101.6 –330/1.4–5.2	Brazil/ 4 m.
16.6–21.4	III—209– 425.1 –741/
1.4– 2.4 –4.3
A. hoshinoi van Soest,	Thick incrusting	I—195–280/ 6–15	t: 240–280/3–4	I—45–250/2–5	6–9–10	South India and Sri
Hooper & Hiemstra,	II—70–140/3–5	s: 260–450/16–25	II—25–170	Lanka/ Intertidal.
19911	III—190–590/1–3
A. ternatus Ridley ,	Flabellate-vasiform	85–205/2–11	t: 200–280/2–5	I—41–266/1–6	9–22	East African coral coast;
18841	to tubulo-digitate;	s: 139–281/2–14	II—80–770/0.5–5	Seychelles; South India
semi-incrusting	and Sri Lanka/14–80m.
rough surface
A. thielei Lévi , 19581	Thinly encrusting	I—130–188/3–4.5	t: 206–222/ 2–3	I—60–200	7–9	Southern Red Sea; South
II—61–79/1–2	s: 230–296/5–6	II—25–70	India and Sri Lanka.
III—240–420
A. wolffgangi Keller ,	uninformed	I—220–277/10–16	t: 250–290/3–4	I—40–150	19–24	Southern Red Sea;
1889 (Siboga speci-	II—80–108/ 2–3	s: 340–445/ 21–33	II—20–200	Western and Northern
men)1	III—350–1000	Madagascar

References: (1) van Soest, Hooper & Hiemstra, 1991 ; (2) Aguilar-Camacho, Carballo & Cruz-Barraza, 2013 ; (3) Zea, 1987 Ecology. Specimen UFPEPOR 4279 was growing on Ircinia felix ( Duchassaing & Michelotti, 1864 ) . Ophiuroids found on specimens UFPEPOR 4275 and 4276. Remarks. The dimensions of the styles are very similar to those reported by Zea (1987) and Ugalde (2021) . However, the specimens studied here are more robust when compared to the micrometries reported in Moraes (2011) , 6– 18.2 –26 vs 2– 10 –12 μm (respectively). The color in vivo usually varies between orange and reddishorange ( Zea 1987 ; Ugalde 2021 ), but Moraes (2011) also recorded yellow. Acarnus innominatus can be confused in the environment with A. microxeatus sp. nov. due to the similarity in their external morphology. However, they differ by the presence of acanthoxeas and smooth microxeas in A. microxeatus sp. nov . This is the first record of the species on the Brazilian continental shelf ( Alagoas State ). The species distribution in the South West Atlantic was previously limited to the oceanic islands off Brazil .