Rhabderemia meirimensis, Cedro & Hajdu & Correia, 2013

Cedro, Victor R., Hajdu, Eduardo & Correia, Monica D., 2013, Three new intertidal sponges (Porifera: Demospongiae) from Brazil’s fringing urban reefs (Maceió, Alagoas, Brazil), and support for Rhabderemia’s exclusion from Poecilosclerida, Journal of Natural History 47 (33 - 34), pp. 2151-2174 : 2158-2164

Rhabderemia meirimensis sp. nov.

Holotype

MNRJ 14275 (cross ref. EH–009), Ponta do Meirim Reef (09 ◦ 32 ′ 35 ′′ S, 035 ◦ 36 ′ 49.14 ′′ W), Maceió (AL, Brazil), intertidal, coll. E Hajdu, VR Cedro and MD Correia, 30 January 2010. Schyzoholotype, UFAL – POR 0575 .

Diagnosis

This is the only Rhabderemia bearing three categories of rhabdostyles and distally microspined sigmas (possibly non-homologous to regular sigmas).

Description

External form and colour: thinly incrusting, relatively large (c. 9 × 9 cm), surface uneven, covered by system of irregular dermal grooves, which do not appear to converge into oscula ( Figure 2B ). Colour alive light-yellow, brown in spirit. Likely osculum about 0.5 mm in diameter apparent on close-up photograph.

Skeleton. Ectosomal skeleton unspecialized, made up by terminal brushes of ascending paucispicular tracts ( Figure 4A ), slightly piercing the surface. Choanosomal skeleton mostly plumose, composed of short, rather straight, ascending paucispicular whispy tracts of rhabdostyles ( Figure 4B ), variably interconnected, densely permeated by sigmas and spirosigmas.

Spicules ( Table 2). Megascleres. Rhabdostyles I, II, III ( Figure 4C–F ), smooth, straight or slightly curved, with markedly rhabdose base, mostly singly bent, occasionally bent twice. Rhabdostyles I, length 335– 399.2 (36)–470 µm, width 14– 16.3 –20 µm. Rhabdostyle II, length 180– 228.2 (30)–290 µm, width 10– 14.1 –17.5 µm. Rhabdostyles III, length 70– 88.6 (13)–120 µm, width 2.5– 6.1 –10 µm. Microscleres. Sigmas ( Figure 4G, H ), s-shaped, distally microspined. Length 40– 56.6 –62 µm. Spirosigmas ( Figure 4I, J ), heavily spined and contorted. Length 3.5– 8.1 –10 µm.

(Continued)

R. bistylifera Lévi, 1961 131– 220 –305/3–6 mst, I, 110– 127 –141/1 W Indian Ocean ( Seychelles) mst, II, 30– 35.8 –43/0.2 sps, 6– 7.7 –10

R. coralloides Dendy, 1924 (sensu Van 206– 310.6 –394/ mst, 37– 40.4 –45/1–1.5 SW Pacific ( New Zealand)

Soest and Hooper, 1993) 13– 24.6 –34 sps I, 6– 9 –11 sps II, 18– 20.3 –22 tho, 32– 32.7 –34/0.5– 1.5 –2.6

R. destituta Van Soest and Hooper , 305– 343.5 –396 no microscleres Tropical E Pacific (Galapagos)

1993

R. fascicularis Topsent,1927 (sensu Van 122– 321.4 –398/8– 13.8 –19 sps, 9– 11.6 –17 NE Atlantic (Azores and Canary Soest and Hooper, 1993) tho, 28– 52 –73 Islands)

R. forcipula Lévi and Lévi, 1989 (sensu 230– 307.2 –381/10– 17.1 –21 mst, 150– 162.5 –171/1–2 Tropical W Pacific ( Philippines) Van Soest and Hooper, 1993) ts, 25– 27 –30

sps, 12– 14.8 –18

R. gallica van Soest and Hooper (1993) 54– 102 –178/4–5 mst, 55– 70.3 –99/0.5–1.5 Mediterranean ( France)

ts, 17–21

R. guernei Topsent, 1890 (sensu Van 183– 363.5 –473/5– 10.3 –15 mst, 65– 87.7 –112/1–2 Lusitanian

Soest and Hooper, 1993) sps, 9– 10.6 –13

tho, 45– 60 –75

R. intexta ( Carter, 1876) (sensu Van 150– 254.3 –350/3.7– 6 –14 tho, 25– 35.4 –60 Lusitanian

Soest and Hooper, 1993) sps, 6– 10.5 –16

R. indica Dendy, 1905 (sensu Van Soest 211– 238.0 –263/5–6.6–9 mst, 42– 46.1 –48/1– 1.25 –2 Indian Ocean ( Sri Lanka and

and Hooper, 1993) sps, 12– 13.2 –15 Thailand)

R. itajai Oliveira and Hajdu, 2005 302– 412.9 –488/ mst, 34– 51.2 –68/1– 1,5 –2 SW Atlantic (S Brazil) 16– 20.3 –24 sps, 5– 6,4 –9

(Continued) (Continued) R. sorokinae Hooper, 1990 (sensu Van 106– 235.1 –283/3– 14 –22 mst, 53– 102 –141/0.8– 1.5 –2 Indo W Pacific (NE Australia and Soest and Hooper, 1993) sps, 6– 12.2 –15 Papua New Guinea)

t, 18– 39.4 –72

R. stellata Bergquist, 1961 (from Van 200–356/12–23 mst, 36–48/3–4 SW Pacific ( New Zealand)

Soest and Hooper, 1993) sps, 10–17

R. spirophora ( Burton, 1931) (sensu 240– 263 –286/6–8.3–9 mst, 45– 53.3 –61/0.5– 0.9 –1.6 SW Indian Ocean ( South Africa) Van Soest and Hooper, 1993) sps, 6– 8.2 –10

R. topsenti Van Soest and Hooper , 145– 215.9 –315–/2.5– 6.6 –10.5 mst, 36– 42.7 –50/0.5– 1 – 1.5 W Mediterranean ( Italy), W 1993 sps, 5– 7.7 –10 Africa ( Ghana)

R. toxigera Topsent, 1892 (sensu Van I, 225– 305.8 –407/ mst, 52– 60 –69/1– 1.3 –2 W Mediterranean( France)

Soest and Hooper, 1993) 9– 9.4 –11 sps, 5– 9.3 –12

II, 126–137/ 5–6 t, 30– 45.6 –57/1

R. uruguaiensis Van Soest and Hooper, I , 166– 231 –310/17– 11 –15 mst, 43– 49.4 –60/0.5– 0.9 –1 SW Atlantic ( Uruguay)

1993 II, 141– 147 –150/2– 2.7 –3 sps, 6– 9.3 –12

sensu Oliveira and Hajdu (2005) 98– 221 –429/5– 10 –19 mst, 25– 42.5 –53/1– 1.4 –2 SW Atlantic (S Brazil)

sps, 5– 7 –10

sensu Hajdu and Desqueyroux– 74– 240.5 –336/9.6– 12 –16 mst, 26– 39.7 –51 SE Pacific (Chilean Patagonia)

Faúndez (2008) sps, 5– 7.9 –10

Ecology

A single specimen was found in our surveys of the sponge fauna of Maceió City’s coastal reefs. It occurred in grooves on the underside of a medium-sized coral boulder beside serpulid polychaete tubes, other demosponges, such as Mycale alagoana Cedro et al. 2011 and Mycale sp. (probably M. (Aegogropila) escarlatei Hajdu et al. 1995 or M. (Naviculina) diversisigmata van Soest, 1984 ), and the foraminiferan Homotrema rubrum (Lamarck) .

Distribution

The species is provisionally a Brazilian endemic, so far known only from its type locality (intertidal Maceió’s reefs – Ponta do Meirim, Figure 1C ).

Remarks

This is the first shallow-water, reef Rhabderemia found in the Tropical southwest Atlantic, a similar niche to that occupied by Rhabderemia minutula ( Carter, 1876) in the Greater Caribbean area ( van Soest & Hooper 1993). Table 2 contrasts the Alagoas’ species to the additional 29 known species of Rhabderemia , and clearly shows how well distinguished it is from its congeners through its three categories of rhabdostyles, lack of microstyles and unique possession of sigmas. The latter, by their distal microspination resemble very similar microscleres seen in the former Desmacellidae [ Biemna microacanthosigma Mothes et al. 2004 (original description); Desmacella pumilio Schmidt, 1870 , sensu Cosme and Hajdu (2010); Neofibularia nolitangere ( Duchassaing & Michelotti, 1864) , sensu Hartman (1967); Sigmaxinella cearense Salani et al. 2006 (original description)]. This finding reinforces the argument of van Soest and Hooper (1993) for the affinity of Rhabderemiidae and Desmacellidae , recognized on the supposition that the microspined microstyles of the former might be homologous to the rugose commata seen here and there in the latter.

The terminally microspined sigmas may actually be examples of “pseudosigmas”, which recalls the argument of Fromont and Bergquist (1990) on convergent morphological evolution in Porifera. This is so because recent molecular results derived from distinct markers have found evidence of a non-poecilosclerid nature for taxa devoid of chelae, once thought to belong in this order. Erpenbeck et al. (2007) found this evidence in cytochrome oxidase subunit 1 (CO1) sequences of Neofibularia Hechtel, 1965 ; Morrow et al. (2012), working with Biemna Gray, 1867 , and Vargas et al. (2013), on Rhabderemia , reached similar conclusions on the basis of CO1 and 28S ribosomal RNA sequences. Finally, Redmond et al. (in press), working on 18S ribosomal DNA produced comparable results for Sigmaxinella Dendy, 1897 . These taxa are nesting closer to tetractinellid sponges. They all share the possession of terminally microspined “sigmas”. They are all still assigned to Poecilosclerida in the World Porifera Database, but this is likely to change soon. Curiously, Desmacella Schmidt, 1870 , may also bear terminally microspined “sigmas”, but nests at the base of the Poecilosclerida . Its assignment to this order receives varied support, depending on the comprehensiveness of outgroup selection (Hajdu et al. in press; Redmond et al. in press).

Figures

Figure 1. Map showing South America and Brazil, with Alagoas state in black (upper left), an expanded Alagoas state with Maceió city in black (upper middle), and the collecting localities off Maceió ((A) Piscina dos Amores; (B) Riacho Doce; (C) Ponta do Meirim; (D) Ponta do Prego).

Figure 2. In situ photographs of the new species described in this study. (A) Plakina coerulea sp. nov. (holotype, MNRJ 14295 at Piscina dos Amores); (B) Rhabderemia meirimensis sp. nov. (holotype, MNRJ 14275 at Ponta do Meirim); (C) Mycale (Aegogropila) rubra sp. nov. (paratype, MNRJ 14050 at Praia do Francês). Scale bars: 1 cm.

Figure 4. Rhabderemia meirimensis sp. nov. (holotype, MNRJ 14275). (A) Ectosomal skeleton; (B) choanosomal skeleton; (C, D) rhabdostyles I; (E) rhabdostyle II; (F) rhabdostyle III; (G) distally microspined sigma; (H) details of microspined terminations of sigmas; (I, J) spirosigmas. Scale bars: A, B, 200 µm; C–F, 100 µm; G, 20 µm; H–J, 5 µm.