Adeonellopsis pentapora Canu & Bassler, 1929

Hirose, Masato, 2016, Diversity and distribution of adeonid bryozoans (Cheilostomata: Adeonidae) in Japanese waters, European Journal of Taxonomy 203 (203), pp. 1-41 : 17-19

Adeonellopsis pentapora Canu & Bassler, 1929

Fig. 11

Adeonellopsis pentapora Canu & Bassler, 1929: 382 , pl. 53, figs 1–5.

Adeonella tuberculata – Ortmann 1890: 53, pl. 4, figs 9a–b. — Okada 1923: 231. — Kataoka 1961: 264, pl. XXXVII, fig. 2.

Adeonellopsis pentapora – Sakakura 1935: 115. — Kataoka 1961: 264, pl. XXXII, fig. 10.

Adeonellopsis yarraensis – Harmer 1957: 799, pl. LIII, figs 18–19 [in part]. — Hirose 2010: 52, pl. 89, figs A–D.

Material examined

JAPAN: colony in Döderlein Collection at MZS, from Sagami Bay, 1882 ( MZS 2-1, MZS 2-2; SEM specimen NSMT-Te748); colonies from east side of Sagami Bay and Sagami Sea, collected by NSMT (NSMT-TeS19, TeS20, TeS21, TeS22); specimens from off Ohakozaki, Otsuchi, 70–77 m depth (NSMT- Te761, Te762, Te765, Te766); Ariake Sea (NSMT-Te767, Te769); Wakasa Bay, Sea of Japan, 70–85.7 m depth (NSMT-Te800); off Shimoda (NSMT-Te892); near Yakushima and Tanegashima, 108–122 m depth (NSMT-Te763, Te764); off Iejima Island, 94–95 m depth (NSMT-Te801); Ogasawara, 136–141 m depth (NSMT-Te768).

Measurements

Autozooids. ZL: 337̅572 (434±54); ZW: 227̅367 (291±35); n = 34. SOrL: 42̅95 (58±10); SOrW: 65̅120 (89±13); n = 34. SAvL: 36̅84 (61±9); SAvW: 25̅51 (38±7); n = 36. SpL: 48̅153 (88±24); SpW: 43̅111 (75±18); n = 37.

Description

Colony yellow or white, small, fragile, dichotomously branching, almost two-dimensional ( Fig. 11 A– B); up to 3 cm high. Branches flat, slender, 1.3–2.6 mm wide (average 1.9 mm; n = 16). Autozooids on both sides of branches; oval or hexagonal, zooidal boundaries distinct, zooids delineated by groove and suture line ( Fig. 11E ). Frontal shield minutely granulate, with marginal pores; sometimes bearing 2 or 3 low, umbonate processes along lateral or proximal margin ( Fig. 11D ), 40–80 μm in diameter (average 60 μm, n = 14). Spiramen large, circular, divided into 4̅6 small denticulate pores ( Fig. 11D ). Peristome present, broadly oval in outline, not tubular ( Fig. 11C ); orifice indistinct in frontal view, proximal margin highly convex ( Fig. 11C ). One or two small suboral avicularia between orifice and spiramen ( Fig. 11E ); if single, positioned near midline and pointing distally or angled slightly distomedially or distolaterally; if paired, pointing distomedially; mandible short-triangular; crossbar incomplete. One to three frontal avicularia similar in size and shape to suboral avicularia situated around proximal and proximolateral margins of zooid ( Fig. 11D ). Basal part of colony consists of autozooids and kenozooids; 309–521 μm long (average 415 μm) by 202–383 μm wide (average 244 μm) (n = 14). Basal autozooids heavily secondarily calcified; peristome and spiramen depression confluent, forming single oblong depression that also contains the suboral avicularia ( Fig. 11F ), common opening 112–203 μm long (average 146 μm) by 66–108 μm wide (average 89 μm) (n = 10). Gonozooids lacking. Marginal vicarious avicularia not observed.

Remarks

Ortmann (1890) reported this species as Adeonella tuberculata ( Busk, 1884) from Sagami Bay based on Döderlein’s specimens, as it has two small avicularia between the orifice and spiramen. Adeonellopsis pentapora is quite small and fragile compared to the other adeonid species collected from Sagami Bay; it also occupies unstable substrates such as hydroid stems ( Fig. 11B ) and gastropod shells ( Fig. 11A ). Sakakura (1935) also reported a colony encrusting a gastropod shell from Toyama Bay. A colony of A. pentapora in the Döderlein collection is encrusted on a small shell of a dead gastropod inhabited by a hermit crab, and a colony collected from Sagami Bay in 2002 is encrusted on a different species of small shell of a dead gastropod. Canu & Bassler (1929) reported Adeonellopsis pentapora from a broad area of the Indo-Pacific, including Japan (Tsugaru Strait). Harmer (1957) considered Adeonellopsis pentapora and A. tuberculata to be junior synonyms of Adeonellopsis yarraensis (Waters, 1881) based on having two small suboral avicularia and narrow branches. A. yarraensis , however, is currently regarded as a strictly fossil species and A. tuberculata as a Recent species in Australia; therefore, I consider A. pentapora to be a valid species.

Distribution

Philippines and Japan: detected in this study from Sagami Bay, Sagami Sea, Korea Strait, Wakasa Bay, Toyama Bay, Otsuchi, Ariake Sea, near Tanega-shima and Yaku-shima, and Ogasawara, at depths of 29– 274 m. Adeonellopsis pentapora was not as abundant as other adeonid species in any collections or at any localities. Kataoka (1961) reported a fossil specimen from the Pleistocene Ryukyu Limestone of Kikai-jima, Kagoshima.

Figures

Fig. 11. Adeonellopsis pentapora Canu & Bassler, 1929. A. Left, colony in Döderlein Collection (MZS 2-1); right, colony collected by NSMT (NSMT-TeS22). B. Colony on hydroid stalk, from Sagami Bay (NSMT-TeS20). C. Distal end of branch showing young autozooids with multiporous, denticulate spiramen (NSMT-Te761). D. Young autozooids with umbonate processes on frontal shield (NSMT- Te764). E. Mature autozooids with small suboral and other frontal avicularia (NSMT-Te761). F. Old autozooids, showing deeply immersed spiramen and orifices (NSMT-Te762).A–B = optical photographs; C–F = SEM images. Scale bars: A = 3 mm; B = 2 mm; C–D, F = 200 μm; E = 250 μm.