Adeonella lichenoides

Adeonella cf. lichenoides (Lamarck, 1816)

Figs 2–3

cf. Eschara lichenoides Lamarck, 1816: 176.

cf. Eschara platalea Busk, 1854: 90, pl. 105, figs 1–3, pl. 108, fig. 4.

cf. Adeonella lichenoides – Harmer 1957: 799. — Busk 1854: 90, pl. 106, figs 1–3. — Hayward 1988: 126, figs 1C, 2–3.

cf. Adeonella platalea – Busk 1884: pl. 184, pl. 21, figs 4, 4a. — Harmer 1957: 809, pl. LIII, figs 2, 4–12. — Hayward 1983: 582, fig. 1A, C–D.

Adeona japonica – Mawatari 1952: pl. 12, fig. 1 [figured specimen].

JAPAN: Izu, Sagami Sea, Emperor Showa collection (NSMT-BryR292, BryR297, BryR299, BryR303, BryR304, BryR315, BryR317, BryR324 (SEM specimen only), BryR357 (SEM specimen only), BryR358, BryR359, BryR360 (SEM specimen only), BryR365, BryR367, BryR377); Seto, Kii Peninsula (SMBL-Brz.17, some fragments NSMT-Te1049), Aug. 1936, probably specimen studied in Okada & Mawatari (1938); Sagami Bay and Sagami Sea, collected by NSMT (NSMT-TeS13, TeS14, TeS30 (SEM specimen only)); off Shimoda, Izu Peninsula (NSMT-Te891); Koshiki Strait (NSMT-Te752); Ogasawara (NSMT-Te753, Te754, Te755, Te756).

Autozooids. ZL: 298̅526 (411±44); ZW: 203̅317 (239±21); n = 39. SOrL: 44̅92 (68±12); SOrW: 60̅101 (77±10); n = 38. FAvL: 53̅86 (68±9); FAvW: 25̅47 (37±5); n = 32. SpL: 22̅39 (30±5); SpW: 22̅37 (28±6); n = 18.

Gonozooids.ZL: 456̅521 (488±32);ZW:290̅334 (318±24); n= 3. SOrL: 75 ̅77 (76±1); SOrW: 93̅122 (111±16); n = 3. FAvL: 61̅67 (63±3); FAvW: 25̅36 (29±5); n = 4. SpL: 34̅38 (36±2); SpW: 35̅81 (61±23); n = 3.

Colony brown, erect, dichotomously branching, widely and irregularly spreading, forming a threedimensional bushy structure; up to 12 cm in diameter and 10 cm high (Fig. 2A). Branches flattened, multiserial, with zooids opening on both sides, 1.9–4.1 mm wide (average 2.7 mm; n = 39); rounded at end. Autozooids oval or rhomboidal, surrounded by distinct, deep marginal groove (Fig. 2 B–C). Frontal shield convex, entirely covered with minute granules, with about 10 small, circular areolar pores inside each lateral margin, some additional pores in central region, and one large peristomial spiramen proximal to orifice (Fig. 2C). Peristome deep, secondary orifice circular or transversely oval. Frontal avicularia small, 1 to 4 in number, occurring near both margins on frontal shield and oriented inward (Fig. 2C) or distally (Fig. 3C). Gonozooids (Fig. 3A) present in broad region at branch bifurcations and at periphery of branches. Gonozooids larger than autozooids, with broader orifice and swollen, porous frontal shield; peristomial spiramen transversely broad, with median projection from distal margin (Fig. 3A). Vicarious avicularia occur near branch bifurcations, often replaced by gonozooids; elongate, as long as or sometimes longer than autozooids (Fig. 2B), 316̅495 μm (average 390 μm) long by 124̅164 μm (average 140 μm) wide (n = 6). Vicarious avicularian chamber large (Fig. 2 D–E); 425̅814 μm (average 572 μm) long by 228̅340 μm (average 274 μm) wide (n = 6). Rostrum of vicarious avicularia lanceolate, acute, directed distally; variable in form and length, up to 400 μm long. Large, triangular vicarious avicularia also occur along branch edges. In basal part of branches and colony, autozooids often replaced by kenozooids (Fig. 3B); 342̅460 μm (average 388 μm) long by 167̅234 μm (average 192 μm) wide (n = 4).

This species was previously known as Adeonella platalea (Busk, 1854) in Japan. Lamarck (1816) first described Eschara lichenoides from the Indian Ocean, and Harmer (1957) transferred it to Adeonella. Harmer (1957) discussed the high variability in A. lichenoides and A. platalea; although he did not synonymize these species, he noted three groups of A. platalea based on variant forms of vicarious avicularia and mandible. Although Harmer’s concept of the nature of intra- vs interspecific variation was different from that of more recent authors, Hayward (1988) restudied a syntype of Eschara lichenoides and found this specimen to be nearly identical to the paratype of A. platalea, and thus considered A. lichenoides to be a subjective senior synonym. Morphological variation within the extremely broad recorded distribution of this species from East Africa to eastern Australia, however, might indicate the presence of two or more unrecognized species.

Mawatari (1952) reported Adeona (Adeonellopsis) japonica from off Minabe and Shirahama, Wakayama Prefecture, without any description but with a photograph of a single branch in which zooids have a swollen frontal shield with a single spiramen, quite resembling Adeonella. The photograph in Mawatari (1952) may be of a branch of A. cf. lichenoides (Brz.17) in the SMBL collection.

Adeonella lichenoides has previously been reported from the Indo-West Pacific (Philippines, Malay Archipelago, Queensland coast, Torres Strait, northern and western coasts of Australia and Victoria, and eastward to Zanzibar and East Africa) (Hayward, 1988). In Japan, Adeonella cf. lichenoides has been collected from Sagami Bay, Sagami Sea, around the Izu Peninsula, off the Kii Peninsula, the west coast of Kyushu (Koshiki Strait), and Ogasawara, at depths of 3– 328 m. Although Adeonella cf. lichenoides was not collected from the eastern part of Sagami Bay by Döderlein or Doflein, it was very abundant in the western Sagami Sea (in ES collection) such as exposed shallow rocky habitat (3–45 m) at the southernmost part of the Izu Peninsula (Hirose et al. 2012).