Stylopoma sinuata, Rodrigues & Almeida & Vieira, 2020

Rodrigues, Maria J. S., Almeida, Ana C. S. & Vieira, Leandro M., 2020, New species of Stylopoma (Bryozoa, Cheilostomata) from Bahia State northeastern Brazil, Zootaxa 4786 (4), pp. 516-534 : 524-525

Stylopoma sinuata n. sp.

( Fig. 5 A–F; Tables 1, 2)

urn:lsid:zoobank.org:act:D89C72AF-B58B-4860-BD43-E6D2AA05FBE3

Material examined. Holotype: UFBA 2394.1 , Baía de Camamu, Costa do Dendê , Bahia State, Brazil, 13°53’ S; 38°59’ W, 18 m, coll. 2012 by LABPOR-UFBA . Paratypes: UFPE 161 , Baía de Camamu, Costa do Dendê , Bahia State, Brazil, 13°36’ S; 38°46’ W, 50 m, coll. 2004 by LAMEB-UFBA; UFBA 722.4 , UFBA 2869.1 , UFBA 2989.1 , UFBA 3041.2 , UFBA 3309.1 , Baía de Camamu, Costa do Dendê , Bahia State, Brazil, 13°45’ S; 38°56’ W, 12 m, coll. 2004 by LAMEB-UFBA.

Diagnosis. Stylopoma with frontal wall with 58–62 pseudopores; primary orifice with a broad and V-shaped sinus and moderate subrectangular condyles with smooth and unlipped margins; adventitious avicularium single, with almost rounded rostrum; vicarious avicularia spatulate in frontal view; ovicell with pseudoporous and tubercular surface and semicircular opening.

Etymology. The species name ‘ sinuata ’ refers to the distinct broad and V-shaped sinus of the primary orifice.

Description. Colony encrusting, uni to multilaminar. Autozooids subrectangular to subquadrangular ( Fig. 5A, B ), limited by slightly raised lateral walls. Frontal wall with smooth calcification except around the orifice, sometimes developing a pointed suboral umbo with nodular calcification, with a reticulate aspect, 58–62 large frontal pseudopores placed in deep cavities, marginal pores distinctly elongated and well-spaced. Primary orifice transversely D-shaped ( Fig. 5C ), wider than long, distal margin smooth; proximal edge with a median broad and V-shaped sinus more than 1/3 of the orifice length; a pair of moderate proximolateral subrectangular condyles [0.007 –0.011 mm high (0.009 ± 0.013; n = 10)] with smooth and unlipped margins. Secondary orifice slightly elevated, formed by a complete collar of granular calcification around the primary orifice. Adventitious avicularia small ( Fig. 5B, C ), single, placed proximolaterally or mediolaterally to the orifice and distally or distolaterally oriented; rounded, with complete crossbar and elliptical foramen. Vicarious avicularium large ( Fig. 5D, E ), same length or slightly shorter than autozooids; slightly spatulate in frontal view, proximal region semicircular, spatulate rostrum, palate occupying less than half of rostrum length, complete crossbar and elliptical elongated foramen. Ovicells prominent ( Fig. 5E, F ), obscuring the orifice of the maternal zooid; ooecium globose, with pseudoporous and tubercular surface; semicircular opening, with entire proximal labellum and without a distinct suture, visible in frontal view.

Remarks. Among Stylopoma species worldwide, only Stylopoma novum Tilbrook, 2001 and Stylopoma viride ( Thornely, 1905) have a broad V-shaped sinus similar to that of S. sinuata n. sp. Differences between S. sinuata n. sp. and S. novum include the number of frontal pseudopores (58–62 in S. sinuata n. sp. and 60–80 in S. novum ), condyles ornament (unlipped in S. sinuata n. sp. and lipped in S. novum ), and morphology of the adventitious avicularia (rounded in S. sinuata n. sp. and subtriangular in S. novum ) ( Tilbrook 2001). Stylopoma sinuata n. sp. and S. viride can be distinguished by the number of frontal pseudopores (58–62 in S. sinuata n. sp. and 20–40 in S. viride ), morphology of the primary orifice (wider than long in S. sinuata n. sp. and longer than wide in S. viride ), morphology of the adventitious avicularia (rounded in S. sinuata n. sp. and acute triangular in S. viride ), and morphology of vicarious avicularia (spatulate in S. sinuata n. sp. and triangular in S. viride ) ( Tilbrook 2001).

Other congeners reported in Brazil can be also distinguished from S. sinuata n. sp. in having a primary orifice with narrow U-shaped ( S. aurantiacum , S. hastata and S. multiavicularia n. sp.), drop-shaped ( S. rotundum , S. corallinum n. sp. and S. faceluciae n. sp.) or somewhat funnel-shaped sinus ( S. carioca and S. variabilis ). Other differences between S. sinuata n. sp. and these species include the length of the vicarious avicularium (varying from 0.262 to 0.374 mm in S. sinuata n. sp. and reaching more than 0.400 mm in all other species), and length and width of the ovicells (never reaching more than 0.400 mm in S. sinuata n. sp. and typically more than 0.400 mm in length and width in all other congeners from Brazil) ( Winston et al. 2014; Ramalho et al. 2018).

Distribution. Brazil: Bahia State. Stylopoma sinuata n. sp. is known only from Baía de Camamu, Costa do Dendê, among 12–50 meters depth, encrusting coral and sponge reefs.

Figures

FIGURE 5. Stylopoma sinuata n. sp., UFBA 2394.1, holotype. A. Subrectangular autozooids. B. Close-up of autozooids. C. Primary orifice and adventitious avicularium. D. Vicarious avicularium. E. Group of zooids with broken ovicells and a vicarious avicularium. F. Detail of broken ovicell. Scale bars: A. 1 mm; B, E. 400 µm; C. 100 µm; D, F. 200 µm.