Plesiocleidochasma infundibulum, Almeida & Larré & Vieira, 2021

Almeida, Ana C. S., Larré, Igor R. N. M. & Vieira, Leandro M., 2021, Ten new species of marine bryozoans (Gymnolaemata: Cheilostomatida) from Brazil, Zootaxa 5048 (4), pp. 511-537 : 520-521

Plesiocleidochasma infundibulum n. sp.

( Fig. 5A–D )

urn:lsid:zoobank.org:act:DAB32BED-C66D-459E-B104-41BC2B9510BE

Material examined. Holotype: UFBA 2991.5 , 1246 ’ S, 3807’ W, Camaçari, Costa dos Coqueiros, Bahia, Brazil, 25 m, coll. by LAMEB-UFBA, 2002 . Paratypes: UFBA 2993.2 , 1245 ’ S, 3806’ W, Camaçari, Costa dos Coqueiros, Bahia, Brazil, 22 m, coll. by LAMEB-UFBA, 2003 ; UFPE 908 , 449 ’–510’ S, 3610’– 3650’ W, Bacia Potiguar, Rio Grande do Norte, Brazil, coll. by Petrobras, 2009–2010 ; UFBA 2888.4 , 1307 ’ S, 3838’ W, 13–21 m, Baía de Todos os Santos , Bahia, Brazil, coll. by Ricardo Miranda, 2017 . Additional specimens: UFBA 3680 , UFBA 3695 , UFBA 3698.1 , UFBA 3702 , 1244–1245 ’ S, 3805’–3807’ W, Camaçari, Costa dos Coqueiros, Bahia, Brazil, 22–23 m, coll. by LAMEB-UFBA, 2000–2007 ; UFBA 3628.1 , UFBA 3628.2 , UFBA 3628.3 , 1307 ’ S, 3838’ W, 13–21 m, Baía de Todos os Santos , Bahia, Brazil, coll. by Ricardo Miranda, 2017 ; UFBA 3646 , UFBA 3644 , 0503 ’ S, 3619’ W, 50–53 m, Guamar , Rio Grande do Norte, Brazil, coll. 2005 .

Diagnosis. Plesiocleidochasma with encrusting colonies of zooids with imperforate frontal shield except for 2–3 small circular areolar-septular pores, keyhole-shaped primary orifice with broad, slightly concave to almost straight proximal sinus margin, downcurved subtriangular condyles, three oral spines, single small adventitious avicularia with subovate profile with acute tip, well-developed distal cryptocyst and small inverted funnel-shaped opesia.

Type locality. Camaçari , Bahia, Brazil .

Etymology. Latin infundibulum , neuter, funnel, alluding to the funnel-shaped outline of the avicularian palatal foramen, which is characteristic of this species.

Description. Colony encrusting, unilaminar ( Fig. 5A ).

Autozooids subhexagonal, globular or irregularly polygonal (0.358–0.451– 0.633 mm long, n = 30, SD = 0.053 mm; 0.323–0.406– 0.429 mm wide, n = 30, SD = 0.049 mm), not well delimited but separated by shallow grooves and inconspicuous sutures ( Fig. 5B ). Frontal shield slightly rugose and finely granulated, with large, rounded tubercles at the zooidal corners and usually a median tubercle; imperforate except for 2–3 small rounded areolar-septular pores, often placed medially near the zooidal margin (rarely the proximal margin). Primary orifice keyhole-shaped (0.126–0.150– 0.178 mm long, n = 30, SD = 0.012 mm; 0.105–0.136– 0.154 mm wide, n = 30, SD = 0.010 mm), distal margin semicircular, proximal sinus margin shallowly concave to almost straight and narrower than the distal region of the orifice ( Fig. 5C ), poster about 0.030–0.035– 0.037 mm long; three oral spines ( Fig. 5C ), becoming concealed by increasing calcification ( Fig. 5B, D ); a pair of subtriangular condyles hooked downwards ( Fig. 5C ).

Adventitious avicularia may occur on some zooids, single (0.108–0.122– 0.131 mm long, n = 12, SD = 0.007 mm; 0.055–0.065– 0.074 mm wide, n = 12, SD = 0.004 mm), placed proximolateral to the orifice; rostrum laterally directed, sometimes tilted distally or proximally, having subovate profile with acute tip; cryptocyst well developed distally; palatal foramen having outline of funnel; complete crossbar without columella.

Ovicell immersed (0.198–0.215– 0.234 mm long, n = 6, SD = 0.012 mm; 0.217–0.251– 0.296 mm wide, n = 6, SD = 0.032 mm); ooecium with same calcification as the frontal shield; labellum subrectangular ( Fig. 5D ).

Remarks. Like P. brasiliensis n. sp., P. infundibulum n. sp. belongs to a group of species (including P. arcuatum , P. foliosum , P. mediterraneum , P. porcellaniforme and P. porcellanum ) with small latero-oral avicularia having a triangular rostrum. Plesiocleidochasma infundibulum n. sp., however, is distinguished from all these congeners by having frontal-shield convexities and an orifice with almost straight to slightly concave proximal sinus margin; in all other species there are no frontal convexities, and the proximal margin of the sinus is distinctly rounded ( Berning 2012; Pizzaferri & Berning 2007; Soule et al. 1991; Winston et al. 2014).

Differences between P. infundibulum n. sp. and P. brasiliensis n. sp. include the primary orifice (with proximal sinus margin shallowly concave to almost straight in P. infundibulum n. sp. and with a deeper U-shaped sinus in P. brasiliensis n. sp.), number of oral spines (3–4 in P. brasiliensis n. sp. and three in P. infundibulum n. sp.), number of marginal pores (2–3 in P. infundibulum n. sp. and 3–6 in P. brasiliensis n. sp.), shape of avicularium palatal foramen (narrow and funnel-shaped in P. infundibulum n. sp., but broad and triangular in P. brasiliensis n. sp.), and the ovicell labellum (subrectangular in P. infundibulum n. sp. and semicircular in P. brasiliensis n. sp.).

Distribution. Western Atlantic: Brazil (Bahia and Rio Grande do Norte). Plesiocleidochasma infundibulum n. sp. can be found encrusting natural and artificial hard substrata; 13‒ 53 m.

Figures

FIGURE 5. Plesiocleidochasma infundibulum n. sp., UFBA 2991.5, holotype. A. Overview of an encrusting colony. B. Group of autozooids. C. Detail of primary orifice. D. Group of ovicelled zooids. Scale bars: A. 500 µm; B. 400 µm; C, D. 200 µm.