Turbicellepora hansenae Denisenko 2016

Turbicellepora hansenae Denisenko, 2016

(Fig. 4)

Turbicellepora (Schismopora) tuberosa: Hansen 1962: 47 ‒48. Turbicellepora hansenae Denisenko, 2016: 189 ‒190, fig. 2.

Material examined. Holotype: ZMUC-BRY-104 fragment of colony (figured specimen), 60°22’3’’ N, 48°22’19’’ W, 886‒932 m, March 2012. Canadian Coast Guard Ship Martha Black. Additional material: ZMUC-Bry-112, three colonies on polychaete tubes (one specimen figured), Stn 179, 63°36’ N, 55°15’ W, 1200 m, 15 August 1928, Davis Strait. Vessel Godthaab.

Distribution. Bathyal Zone of Davis Strait, off the southwestern coast of Greenland.

Description. Colony encrusting. AutoZooids rectangular to hexagonal, separated by grooves, flattened in the unilaminar area, more convex in the multilayered part (Fig. 4a‒b). Frontal shield thick, with sparse marginal areolar pores. Orifice wider than long, with wide, shallow U-shaped sinus occupying more than half the proximal rim, surrounded by a relatively high, flared peristome (Fig. 4c‒d). Asymmetrical suboral avicularium with prominent columnar cystid associated with peristome; cystid chamber connected to maternal autoZooid via 2‒3 areolar pores (Fig. 4a‒d). Crossbar complete, lacking columella; rostrum slightly hooked and inclined upward towards the orifice; mandible triangular. Single or paired distolateral avicularia originating from lateral perioral areolar pores in ovicellate Zooids, their long, tubular, curving cystid variable in length, incorporated in peristome and appressed to ooecium. Crossbar complete, mandible semioval (Fig. 4a). Both suboral and distolateral avicularia with pore near the base, connecting avicularian cystid with autoZooidal coelom. Drop-shaped interZooidal avicularia immersed or prominent, with flattened frontal surface, wide palate and complete crossbar (Fig. 4e‒f). Ovicell hyperstomial, non-cleithral; ooecium globular or elongated. Ectooecium smooth, unevenly perforated by 10‒25 pseudopores of irregular shape. Medial ‘fold’ of variable thickness present on ectooecium surface. Ancestrula not observed. For a more detailed description of the type specimen and its measurements see Denisenko (2016).

Remarks. Unfortunately, Hansen’s material loaned from the Zoological Museum, University of Copenhagen, was in poor condition, with parts of the Zooids broken. Notwithstanding, SEM images clearly show a correspondence of characters with the type material of Turbicellepora hansenae. The suite of diagnostic characters, (namely orifice, sinus, peristome, avicularia and ovicells) of the specimens described as T. tuberosa (Smitt, 1868) by Hansen (1962) is equivalent to that in the type specimen of T. hansenae (Fig. 4), although siZe of morphological characters varies but within the standard deviation. Both sets of examined specimens from Davis Strait have large, prominent suboral avicularia with a wide base, and complete crossbar without a columella (Fig. 4a, c, e, g). Both have curved, distolateral avicularia associated with ooecia, character that distinguish the species from many congenerics. Also, the drop-like shape, complete cross-bar and wide palate of the interZooidal avicularia are very similar. Both sets of specimens have similar ooecium shape, which can have a medial ‘fold’ of variable thickness in different ooecia. The most significant discrepancy is the number of ooecial pseudopores. Nevertheless, the close similarity of all the other morphological features allows to consider the specimens described by Hansen (1962) as T. tuberosa (Smitt, 1868) as belonging to T. hansenae.

FIGURE 4. Comparison of morphological characters in Turbicellepora hansenae Denisenko, 2016, specimen ZMUC-BRY- 112, southern part of Davis Strait, 1200 m (a, c, e, g) and holotype ZMUC-BRY-106, southern part of Davis Strait, 865‒943 m (b, d, f, h). a–b, group of autozoids; c–d, orifice; e–f, interzooidal avicularia; g–h, suboral and distolateral avicularia and ooecia.