Aetea ligulata Busk, 1852

Taylor, Paul D. & Tan, Shau-Hwai Aileen, 2015, Cheilostome Bryozoa from Penang and Langkawi, Malaysia, European Journal of Taxonomy 149, pp. 1-34 : 5-6

Aetea ligulata Busk, 1852

Fig. 2 A–F

Aetea ligulata Busk, 1852: 31 , pl. 42.

Aetea ligulata – Osburn 1950: 13, pl. 1, fig. 4.

Material

MALAYSIA: MSL BRY001a, Pantai Pasir Hitam, Langkawi, collected intertidally from coral reef, fouling Hippopodina feegeensis . MSL BRY002, Kampung Kuala Temoyong, Langkawi, encrusting shell found among fishing debris.

Description

Colony encrusting, uniserial, runner-like with widely spaced branches ( Fig. 2 A–B), delicate, feebly calcified. Autozooids slender with elongate pyriform proximal base and an erect distal part; proximal base 1.1–1.3 mm long by about 0.13 mm maximum width ( Fig. 2C ), with irregular transverse growth wrinkles and locally minutely porous or with finely reticulate ornamentation, a narrow proximal cauda of about same length as broader distal part; erect part often broken off or collapsed, about 0.42 mm long by 0.07 mm maximum width, proximally with widely spaced, hoop-like annulations about 0.02 mm apart ( Fig. 2D ), expanding a little distally where an elongated opesia, 0.25 mm long by 0.05 mm wide, is developed on proximal-facing side ( Fig. 2E ).

Remarks

This species was erected by Busk (1852) based on material collected by Charles Darwin from the coast of Patagonia and the Magellan Strait. Busk’s figure shows clearly the coarsely annulated erect parts of the zooids, very different from the finely striated annulations seen in the two common cosmopolitan species Aetea anguina ( Linnaeus, 1758) and A. sica (Couch, 1844) . A modern systematic study of Aetea combining morphological and molecular data is required and in the meantime there must be reservations about the identities of species with such seemingly wide latitudinal distributions as A. ligulata .

Abundant evidence of damage and repair can be observed in the skeleton. The skeletons of some zooids were apparently partly destroyed, eliciting reparative growth, sometimes on multiple occasions ( Fig. 2C ). Broken zooids may also reveal internal stolon-like structures ( Fig. 2F ), indicating growth through the dead zooid to re-establish connections between zooids and allow growth from the open ends of branches. Although the straggly, runner-like form of Aetea and various other uniserial cheilostomes would suggest a reduced commitment to maintaining the integrity of the colony, reparative growth that renews links between zooids and re-uses substrate space once occupied by dead zooids is a common feature of such bryozoans, Recent and fossil ( Taylor 1988).

Figures

Fig. 2. Aetea ligulata Busk, 1852. A. Colony fouling Hippopodinella feegeensis; Pantai Pasir Hitam, Langkawi, MSL BRY001a. B–F. Kampung Kuala Temoyong, Langkawi, MSL BRY002. B. Zooids growing aroung clionid-bored shell. C. Zooid with repaired skeleton. D. Erect part of zooid collapsed against substrate to reveal annulations on distal side. E. Erect part of zooid collapsed to show opesia on proximally facing side. F. Broken zooid showing intramural ‘stolon’. Scale bars: A–B = 1 mm; C–E = 200 μm; F = 100 μm.