Biflustra sphinx, Vieira, Leandro M., Almeida, Ana C. S. & Winston, Judith E., 2016

Vieira, Leandro M., Almeida, Ana C. S. & Winston, Judith E., 2016, Taxonomy of intertidal cheilostome Bryozoa of Maceió, northeastern Brazil. Part 1: Suborders Inovicellina, Malacostegina and Thalamoporellina, Zootaxa 4097 (1), pp. 59-83 : 68-69

Biflustra sphinx n. sp.

( Figs. 15–17 )

? Acanthodesia cf. irregulata: Taylor & Tan, 2015: 9 , fig. 3G–L. [ Malaysia] Non Membranipora irregulata Liu, 1992 , 124, figs. 14–17. [ China]

Material examined. Holotype: UFPE 0 55, Sobral sewer outfall, Maceió, Alagoas, Brazil, 9º40'45" S, 35º45'01" W, intertidal, erect colony on hydroids, coll. 21 October 2009 by L.M. Vieira & M.D. Correia. Paratype: UFBA 1599, same data as holotype.

Diagnosis. Biflustra with encrusting colonies, multiserial, becoming erect and bilaminar; cryptocyst surrounding almost entire opesia length, shorter laterally than proximally, without denticles. Frontal membrane smooth. Distal transverse walls with a row of uniporous mural septula; lateral walls with two pairs of multiporous mural septula.

Description. Colony white, growing on hydroids, becoming erect, bilaminar. Autozooids subrectangular, 0.332–0.486 mm (0.382 ± 0.044) long and 0.210–0.327 mm (0.239 ± 0.037) wide, distal end rounded and proximal concave. Lateral walls thick, beaded narrow cryptocyst, without sharp denticles on proximal border. Short and thick gymnocystal tubercles with triangular bases often present in one or both outer proximal edges. Opesia occupying 75–90% of zooid length, 0.295–0.375 mm (0.318 ± 0.027) long and 0.163–0.266 mm (0.190 ± 0.030) wide. Operculum with lightly sclerotized outer rim. Frontal membrane smooth, without spinules. Distal transverse walls with a row of uniporous mural septula, often with paired muscle scars set high; lateral transverse walls with two pairs of multiporous mural septula. Early astogeny unknown.

Etymology. Epithet from the Greek Sphinx , female monster of Thebes who propounded riddles, in reference to the confusion in the genus Biflustra .

Remarks. There are some similarities in skeletal zooids of erect colonies of B. sphinx n. sp., B. arborescens and B. irregulata . Winston & Hayward (2012) characterized B. arborescens by having brown chitnous interzooidal lines, spinules on the frontal membrane, brownish opercula, and lack of open triangular tubercles in zooidal corners. These characteristics are also present in B. irregulata (see Seo & Min 2009; Taylor & Tan 2015), but they are not observed in B. sphinx n. sp. The skeletal zooids identified by Taylor & Tan (2015) as Acanthodesia cf. irregulata do not have soft parts, precluding the confirmation of presence of cuticular spinules.

Skeletal zooids of B. sphinx n. sp. resemble those of Biflustra grandicella ( Canu & Bassler, 1929) and Biflustra perambulata Louis & Menon, 2009 in having oval opesia and cryptocyst more developed proximally than laterally, without a median denticulate process such as described in B. marcusi n. sp. Biflustra sphinx n. sp. is distinct, however, in having shorter zooids (0.332–0.486 mm long in B. sphinx n. sp., 0.540–0.600 mm long in B. perambulata , and 0.620–0.960 mm long in B. grandicella ) and gymnocystal tubercles with a triangular base, absent in both B. grandicella and B. perambulata . Gymnocystal tubercles were also illustrated in Flustra savartii Audouin, 1826 by Savigny (1817, pl. 10, fig. 2b), but were not observed in Recent specimens from Egypt (see above). Specimens assigned to B. savartii from the Northern Bay of Safaga, Egypt ( Ostrovsky et al. 2011, 2016) are also distinct in having multiporous mural septula in distal transverse walls.

Conopeum vaughani ( Canu & Bassler, 1919) , described from Lower Miocene of Dominican Republic, and B. paulensis , described from Brazil, resemble B. sphinx n. sp. in autozooidal size and the presence of gymnocystal tubercles, but they are distinguished by the shape of the autozooid (oval in C. vaughani and B. paulensis , and rectangular in B. sphinx n. sp.) and by the colony form (encrusting and unilaminar on gastropod shells in C. vaughani and B. paulensis , rectangular and forming bilaminar sheets in B. sphinx n. sp.); Biflustra paulensis also has minute proximal cryptocystal denticles projecting into opesia; these are absent in B. sphinx n. sp.

Distribution. Brazil: Alagoas (Maceió). Biflustra sphinx n. sp. is often found growing on hydroids, becoming bilaminar.

Figures

FIGURES 12 – 17. Species of Biflustra from Maceió: 12 – 14, Biflustra marcusi n. sp., UFPE 0 91, holotype, Pratagy, Maceió, Alagoas, Brazil; 12, group of zooids; 13, close-up of autozooid with developed cryptocyst; 14, close-up of distal half of autozooid showing the median cryptocystal denticle and the two sharp denticles projecting obliquely to the midline of opesia; 15 – 17, Biflustra sphinx n. sp., UFBA 1599, paratype, Sobral, Maceió, Alagoas, Brazil, erect bilaminar colony; 15, group of autozooids; 16, close-up of autozooids, showing the tuberculate cryptocyst and gymnocystal tubercles; 17, close-up of vertical wall showing the distal multiporous mural septula.