Bryopesanser inflexus, Martino & Rosso & Taylor & Chiu & Fujita & Kitamura & Yasuhara, 2025

Bryopesanser inflexus sp. nov.

Di Martino, Rosso and Taylor

Figure 40 View FIGURE 40

zoobank.org/ 36CD63CE-E101-4590-A347-9B3002932DF5

Type material. Holotype PMC. B62. 29.7.2024 a, sample 19229; Core 19, Daidokutsu cave, Okinawa, Japan, Holocene.

Etymology. Latin, meaning curved, referring to the peristomial proximal mucro, which is upwardly curved, and the ooecial process, which is downwardly curved.

Diagnosis. Bryopesanser with faintly nodular frontal shield and multiporous pseudopores; orifice with straight proximal margin, longer-than-wide drop-shaped sinus, and minutely denticulate condyles; six oral spines in ovicellate zooids, the proximalmost pair slightly above the proximal margin of orifice; proximal peristome developing a narrow, median mucro curved upward; paired avicularia distolateral to orifice, aligned with the second proximalmost pair of spines, pear-shaped; rostrum open, distomedially directed; ooecium nodular, imperforate, with proximal projection curved downward.

Description. Colony encrusting, multiserial, unilaminar. Autozooids distinct, separated by raised sutures and shallow grooves, pentagonal, slightly longer than wide (mean ZL/ZW 1.09), widest proximally, with thick lateral walls (175–225 µm); small, subcircular pore-chamber windows visible distally and distolaterally, approximately 30 µm in diameter. Frontal shield flat to slightly convex, convexity more obvious around the orifice, faintly nodular, densely pierced by multiporous pseudopores, 17– 19 µm in diameter; a few marginal areolae also present at proximal and proximolateral zooidal corners, often obliterated by sediment. Orifice with semicircular anter, straight proximal margin occupied by rectangular, minutely denticulated condyles, 10 µm high, and longer-than-wide drop-shaped sinus, 45–50 µm long by 30–35 µm wide; six spine bases in ovicellate zooids, 25–40 µm in diameter, with the proximalmost pair slightly above the proximal margin of the orifice; proximal peristome 200–230 µm wide, developing into a narrow, squared, median mucro curved upward. Avicularia adventitious, paired, located distolaterally to orifice, aligned with the second proximalmost pair of spines, pear-shaped; rostrum open, distomedially directed; crossbar complete. Ovicell hyperstomial; ooecium cap-like, smooth, nodular, imperforate, with thick proximal margin developing into a narrow, squared, median projection curved downward. Measurements (µm). ZL 764±16, 753–776 (1, 2); ZW 699±92, 634–764 (1, 2); OL (including sinus) 168±18, 156–181 (1, 2); OW 151±15, 141–162 (1, 2); AvL 128±9, 111–137 (1, 6); AvW 101±4, 95–105 (1, 6); OvL 176±17, 157–189 (1, 3); OvW 217±30, 183–236 (1, 3).

Remarks. Bryopesanser inflexus sp. nov. is distinguishable from all known species of Bryopesanser developing a suboral mucro. In Bryopesanser pesanseris ( Smitt, 1873) from the Atlanto-Caribbean area, the frontal shield is densely granular with closely adjacent granules, whereas in the new species it is nodular yet smooth overall. The peristome of the new species produces a narrower mucro and the ooecium is smoother compared to B. pesanseris . Also, the sinus of the new species is deeper and more rounded, differing from the more elliptical sinus of B. pesanseris . Alignment and orientation of avicularia also differ: in the new species, they align with the second proximalmost pair of spines and are distomedially directed, while in B. pesanseris they align with the proximalmost pair of spines and are distally directed. The Indo-Pacific species B. capitaneus Tilbrook, 2006 has the proximalmost pair of spines placed more distally compared to the new species in which this pair is only slightly above the proximal margin of the orifice. Moreover, avicularia alignment in B. capitaneus is as in B. pesanseris . Bryopesanser latesco Tilbrook, 2006 , widespread in the Pacific, differs in having condyles dipping medially and a wider-thanlong sinus and a flared peristome only slightly raised medially; B. tonsillorum Tilbrook, 2012 , widespread in the Indo-Pacific, differs in having distally directed avicularia placed below the proximalmost pair of spines, convex proximal border of orifice, and coarsely denticulate condyles; B. gardineri Tilbrook, 2012 , from the western Pacific, has convex proximal margin of the orifice and serrated avicularia edges; B. hebelomaia Tilbrook, 2012 , found in the South China Sea, has a smaller and shallower sinus, and distally directed avicularia; B. lobiones Tilbrook, 2012 has the proximal margin of the orifice sloping proximally from the midline; B. protrusus Winston and Jackson, 2021 , from Jamaica, exhibits a conical proximal mucro and smooth condyles. The Miocene B. bragai Di Martino and Taylor, 2015 from East Kalimantan ( Indonesia) develops a median mucro but differs in having large and simple circular pseudopores. The only species known from Japan, B. ascendolaris Tilbrook, 2012 , lacks a proximal, median mucro.