Adeonellopsis gracilis Liow & Gordon 2020, n. sp.
Creators: name: Liow, Lee Hsiang
name: Gordon, Dennis P.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Bryozoa
Gymnolaemata
Cheilostomatida
Adeonidae
Adeonellopsis
Adeonellopsis gracilis

description: Adeonellopsis gracilis n. sp.
(Figs 3I, 16, 17C; Tables 1, 2)
Etymology. Latin gracilis, slender, alluding to the thin colony branches.
Material examined. Holotype: NIWA 92745, Stn KAH1206 /4, 40.0140° S, 174.1600°E, South Taranaki Bight,
64 m. Paratypes: NIWA 144899, 146097, 146099, Stn TQI1201/25, 40.0013° S, 174.0112° E, South Taranaki Bight, 82 m. Other: NIWA 146153, Stn W 74.
Diagnosis. Branches slender, mostly 1 mm wide. Autozooids averaging 442 μm long, 222 μm wide. Spiramen longitudinally elongate and subtriangular, mostly with 6 pores. Small suboral avicularia paired, transverse, their acute tips touching. Smaller adventitious avicularia often occurring elsewhere on zooid. No large avicularia or interzooidal avicularia on branch margins. Putative gonozooids with proportionally narrower and wider orifices and larger spiramina with 10 pores.
Description. Mature intact colony not seen. Isolated branches slender, 0.8–1.1 mm wide, mostly 1 mm, more or less bifurcating in more than one plane, twiggy. Colour of dried colony pale creamy-brown.
Autozooids arranged in quincunx; 5–6 longitudinal series across width of branch. Neanic zooids variably elongate-subhexagonal. Interzooidal boundaries indicated by thin lines of calcification in interzooidal furrows, which are bordered by 9–14 small areolar pores (mostly 10–12) in a series around the entire zooidal margin. Autozooids averaging 442 μm long, 222 μm wide in about five series across branch width (Fig. 16A).
Autozooidal peristomial orifice more or less transversely oval to roundly D-shaped, the unbroken distal margin sometimes raised forward and cowl-like; proximal margin straight or weakly concave. Discrete round spiramen lacking; instead, 4–11 spiraminal pores arranged in median longitudinal row, frequently subtriangular (Fig. 16B, E); distribution of pores in proximal direction variable, generally 2-2-1, 1-2-2-1, 2-1-1-1- 1 in neanic zooids; average length 114 μm, width 53 μm. Spiraminal spokes 6–10, varying in length, simple or bifurcate, some touching or overlapping; spiraminal area increasingly sunken as zooids age with some pores immersed in and concealed by calcification.
Suboral avicularia (Fig. 16 B–D) paired (very rarely single), their cystids merged and rostra directed transversely or slightly obliquely toward each other, their tips sometimes touching. In ephebic zooids, orifice, suboral avicularia and spiramina in common furrow. No large avicularia or interzooidal avicularia on branch margins.
Putative gonozooids (Fig. 17C) with proportionally narrower and wider orifices (mean width 103 μm) and larger spiramina with 10 pores.
Ancestrula and early astogeny not seen.
Remarks. Adeonellopsis gracilis n. sp. is wholly endemic to New Zealand. Its branches are as slender as those of A. minor n. sp., but it has the smallest zooids, orifices and suboral avicularia of any of the species described herein. Apart from its diminutive dimensions, the most distinctive zooidal attributes are the elongate-triangular distribution of spiraminal pores and the consistently transverse orientation of the paired suboral avicularia.
An undescribed late Eocene Australian fossil [Brown’s Creek Clay, Aldingan (Priabonian), southwest Victoria], in the collection of P.E. Bock may be an early antecedent of A. gracilis n. sp. —it has slenderer branches with only three longitudinal autozooidal series across the branch width but a similar elongate spiramen.
Distribution. New Zealand: Greater Cook Strait, 32– 80 m. Endemic.
description: Published as part of Liow, Lee Hsiang & Gordon, Dennis P., 2020, New species of Adeonellopsis (Bryozoa: Adeonidae) from southern Zealandia and the western Tasman Sea, pp. 301-331 in Zootaxa 4895 (3) on pages 323-325, DOI: 10.11646/zootaxa.4895.3.1, http://zenodo.org/record/4326650