Pleurocodonellina marcusi, Almeida & Souza & Farias & Alves & Vieira, 2018

Almeida, Ana C. S., Souza, Facelucia B. C., Farias, Jamile, Alves, Orane F. S. & Vieira, Leandro M., 2018, Bryozoa on disarticulated bivalve shells from Todos os Santos Bay, northeastern Brazil, with the description of two new species, Zootaxa 4434 (3), pp. 401-428 : 411-413

Pleurocodonellina marcusi n. sp.

( Fig. 6A–F ; Table 7)

Schizoporella horsti : MARCUS, 1937A: P. 87, PL. 18, fIg. 46; 1938, P. 39; 1939, P. 139, PL. 4, fIg. 13.

Schizoporella horsti : GUIMARãES & ROSA, 1941: P. 308.

Smittina signata : MACHADO & SOUZA, 1994: P. 259.

Rimulostoma horsti : VIEIRA et al., 2008: P. 27.

Rimulostoma horsti : ALMEIDA et al., 2015A: P. 4.

NOT Schizopodrella horsti OSBURN, 1927: P. 127, fIgS 3–5.

Material examined. Holotype: UFBA 1641, on valve of Dallocardia muricata . Paratype: UFBA 1648, on valve of Dallocardia muricata .

Comparative material: USNM 11838 , Schizopodrella horsti , holotype, det. R.C. Osburn, Spanish Water, CuraÇao, coll. May 18, 1920 .

Type locality. Itaparica Beach, Todos os Santos Bay, Bahia State, NE Brazil.

Etymology. Named after Ernst Gustav Goltthelf Marcus (1893–1968) for his invaluable contributions to zoology.

Description. Colony encrusting ( Fig. 6A ), unilaminar. Autozooids ( Fig. 6B ) long-ovoid to hexagonal, surrounded by 16–22 large, marginal pores. Frontal wall centrally imperforate, rough, tessellated. Primary orifice ( Fig. 6C ) subcircular to circular in outline, distal rim smooth, arched, with broad, U-shaped sinus, semicircular in outline, flanked by two small, pointed proximolateral condyles with serrated tips; 1–2 oral spines, mostly obscured later in ontogeny. Secondary orifice ( Fig. 6D ) formed by complete, low collar of calcification around the primary orifice, cormidial (i.e. with a distal contribution from the next distal zooid), sometimes obscuring the primary orifice. Frontal avicularia small, single, located just proximolateral to the orifice on one side, directed proximolaterally; rostrum with long-subtriangular to sublanceolate mandibular portion, foramen oval, crossbar complete, with calcified palate occupying approximately half of avicularium chamber. Other avicularia absent. Ovicell ( Fig. 6D, E ) prominent, surrounded peripherally by frontal calcification from adjacent zooids; ectooecium perforated by 24–42 small rounded pseudopores.

Remarks. Among species in Pleurocodonellina Soule & Soule, 1973, P. marcusi n. sp. most resembles Pleurocodonellina horsti ( Osburn, 1927) , a species traditionally considered to be widely distributed through the Western Atlantic Ocean, including the Caribbean and Brazil ( Marcus 1937a; Winston & Håkansson 1986). Unfortunately, the holotype of P. horsti is mounted in a balsam slide and few fragments remain entire, preventing SEM observation. However, under a stereomicroscope, some morphological characters can be seen to distinguish P. hosti from P. marcusi n. sp. Pleurocodonellina horsti has adventitious avicularia with the rostrum distally acute (rounded in P. marcusi n. sp.); no oral spines are evident in the type of P. horsti ( P. marcusi n. sp. has 1–2 oral spines); the frontal calcification of P. horsti varies from granular to nodular (the frontal wall is tesselated in P. marcusi n. sp.); and P. horsti has a longer primary orifice, about 0.16 mm long ( Osburn 1927) (0.11 mm long in P. marcusi n. sp.).

Brazilian specimens reported by Marcus (1937a, 1938, 1939) as Schizoporella horsti have a semicircular sinus, oblong to sublanceolate avicularia, tessellated frontal wall and smaller orifice than in Osburn’s P. horsti (Marcus 1937a, 1939), and we here reassign them to P. marcusi n. sp. In addition, unregistered specimens in the UFBA collection identified as Smittina signata (recognized as Pleurocodonellina signata (Waters, 1889)) by Machado & Souza (1994) were examined and clearly belong to P. marcusi n. sp. Differences between P. signata and P. marcusi n. sp. include the number of oral spines (1–3 in P. signata , 1–2 in P. marcusi n. sp.), shape of the orificial sinus (drop-shaped in P. signata , semicircular in P. marcusi n. sp.), the presence of large adventitious avicularia (absent in P. marcusi n. sp.) and the number of ooecial pseudopores (60–70 in P. signata , 24–42 in P. marcusi n. sp.).

Pleurocodonellina marcusi n. sp. differs from all congeners in the combination of: semicircular sinus; 1–2 oral spines; small, oblong to sublanceolate avicularium; ooecia perforated by 24–42 small pseudopores. At least three Pleurocodonellina ( P. clavicula Ryland & Hayward, 1992; P. laciniosa Hayward & Ryland, 1995; P. lahainae Soule & Soule, 1973) have dimorphic avicularia and a larger sinus than in P. marcusi n. sp. An acute avicularium and robust condyles are present in P. californica Soule, Soule & Chaney, 1995, P. longirostrata ( Hincks, 1882) , P. macroperforata Tilbrook, 2006 and P. microperforata Tilbrook, 2006 .

Caribbean specimens of Pleurocodonellina are found encrusting clay nodules and sand grains ( Osburn 1927; Winston & Håkansson 1986), and species from the Pacific Ocean are common in coral reefs ( Tilbrook 2006). Along the Brazilian coast, P. marcusi n. sp. had already been reported (as Schizoporella horsti ) attached to crabs ( Guimarães & Rosa 1941). This is the first record of this species living on shells.

Distribution. Atlantic: Brazil (Rocas Attol, Bahia and São Paulo).

Figures

FIGURE 6. Pleurocodonellina marcusi n. sp., HOLOTYPE, UFBA 1641. A. OVERVIEW Of A COLONY. B. GROUP Of AUTOZOOIDS SHOWINg THE SUBTRIANgULAR AVICULARIUM AT ONE SIDE Of THE PERISTOME. C. CLOSE-UP Of A PRIMARY ORIfICE SHOWINg A SINgLE ORAL SPINE BASE, CONDYLES AND SINUS. D. CLOSE-UP SHOWINg A SUBLANCEOLATE AVICULARIUM. E. GROUP Of OVICELLED ZOOIDS. F. CLOSE-UP Of AN OVICELLED ZOOID. SCALE BARS: A, 500 µM; B, D–F, 100 µM; C, 50 µM.