Cellaria macricula, Achilleos & Gordon & Smith, 2020

Achilleos, Katerina, Gordon, Dennis P. & Smith, Abigail M., 2020, Cellaria (Bryozoa, Cheilostomata) from the deep: new species from the southern Zealandian region, Zootaxa 4801 (2), pp. 201-236 : 209-211

Cellaria macricula n. sp.

( Fig. 5 )

Cellaria humilis: Gordon 1984: 58 , plate 18A; Gordon 1986: 76; Gordon et al. 2009: 290. Non C. humilis Moyano 1973 . Cellaria sp. 5: Achilleos et al. 2019: [3–7].

Material examined. Holotype: NIWA 128675 , cruise TAN0413, Stn 130, 37.3557º S, 177.0997º E, Bay of Plenty, 260–280 m, collected 14 November 2004 . Paratypes: NIWA 128657 , cruise TAN1105, Stn 109, 38.2827º S, 173.4490º E, shelf edge NW of Taranaki, 250–365 m, collected 3 April 2011 . Other: Unregistered specimen from NIWA Stn K 7951, 33.0433° S, 179.5767° W, southern Kermadec Ridge , 350 m, collected 18 July 1974 .

Etymology. Latin macriculus, diminutive of macer, macra, - um, lean, thin, alluding to very thin internodes.

Diagnosis. Colony with lateral as well as dichotomous branching. Autozooids back-to-back in pairs, broadening to whorls of 3–4 zooids. Opesia wider than long with denticulate distal and smooth convex proximal rim with knob-like condyles. Interzooidal avicularia with triangular hooded rostrum. Female zooids dimorphic, broader than autozooids with narrowly crescentic-ooecial opening.

Description. Colony erect, flexible, branching laterally and dichotomously; fragments not> 10 mm in length. Stem very slender (W, 170–555 μm), tapering proximally. Zooids arranged back to back in alternating pairs proxi- mally, or 1–2 additional zooids interpolated to make whorls of 3–4; up to 11 or more whorls along the stem.

Autozooids elongate-hexagonal, longer than wide (ZL, 420–602 μm; ZW, 197–399 μm; ratio 2.1). Cryptocyst smooth overall; cryptocystal ridges continuous or nearly so distally, not quite converging proximally, rim slightly scalloped adjacent to opesia, otherwise smooth. Opesia wider than long (OpL, 58–78 μm; OpW, 79–119 μm; ratio 0.72), rim slightly raised, denticulate distally and smooth proximally; convex proximal margin flanked by stout upturned knob-like condyles.

Avicularia not very common, interzooidal, sometimes causing truncation of distal margin of parent zooid. Distal 2/3 comprising hooded rostral area, its semicircular opening strongly inclined frontwards, mostly concealing large rostral foramen. Rostrum directed distally. Mandibular pivots horizontal, raised, not constricting combined palatal- opesial foramen, which is V-shaped proximal of pivots. Cryptocyst more or less inversely semicircular but indented in middle, surface smooth except for weak tuberculation of rim (AvCL, 123–144 μm; AvCW, 102–117 μm; ATL, 99–114 μm; ATW, 78–92 μm; RL, 81–92 μm; RW, 78–92 μm).

Ovicellate parts of internode wider, with zooids in whorls of 4. Female zooids dimorphic, broader than autozooids, with slightly wider opesiae; autozooids just proximal of ovicellate zooids intermediate in size. Frontal face of ooecium smooth, the ooecial opening narrowly crescentic with indented corners (OvApL, 20–23 μm; OvApW, 91; ratio 0.2).

Ancestrula not definitely seen. One stem, almost certainly a lateral branch, has a truncated proximal zooid with an occluded opesia; these branches arise from opesiae of autozooids in the parent stems.

Remarks. Cellaria macricula n. sp. most closely resembles C. humilis Moyano, 1983 , as depicted in his line drawings. The avicularia of this species are reported as triangular with a semicircular mandible, but the rostrum is not hooded. Furthermore, C. humilis branches only laterally while C. macricula n. sp. also branches dichotomously. Moyano (1993, fig. 17) depicts what appear to be two kinds of lateral branch origins—one from an autozooidal opesia and another, with a narrower cuticular tube, from a smaller midfrontal location. Moyano (1991) illustrated by SEM some autozooids, one of which shows an occluded midfrontal rootlet pore. This SEM photo also shows that the opesia in C. humilis has a straight proximal rim and there are no condyles, in marked contrast to C. macricula n. sp.

Distribution. Endemic; southern Kermadec Ridge, Bay of Plenty, Northland west coast, Fiordland, southwest of South Island, 134–549 m depth.

Figures

FIGURE 5. Cellaria macricula n. sp., TAN0413/130. A. Stem with two lateral branches. B. Dichotomously branched internodes and lateral rootlets. C. Proximal end of presumed lateral branch. D. Tetraserial part of stem with ovicellate zooid. E. Close up of an opesia and avicularium. Scale bars: A, B, 500 μm; C, 100 μm; D, 200 μm; E, 50 μm.