Organisms Diversity & Evolution 1 (2001)
Electronic Supplement 5

Verena Häussermann & Günter Försterra:
A new sea anemone from Chile, Anemonia alicemartinae n. sp. (Cnidaria: Anthozoa). An invader or an indicator for environmental change in shallow water?

print version: Org. Divers. Evol. 1(3): 211-224. 2001 (full article)
electr. suppl.: pdf-files and colour pictures (see below)

Abstract

The new species, Anemonia alicemartinae (Actiniidae), is described from rocky shores of north and central Chile. Its members' abundance, occurrence in exposed positions, and bright red colour make it one of the most eye-catching species of northern Chile. The description is based on 74 specimens collected between 1975 and 2001, and on live observations of several hundred animals in their habitats and in aquaria. The natural microhabitats are positions exposed to currents but protected from surge surf, ranging from tide pools down to depths of 16 m. In 1998, the southern distribution limit was 37°S, the southernmost extent of the southerly Chile Coastal Countercurrent. The species is similar to Anemonia natalensis and Pseudactinia varia from South Africa. The most distinctive features of A. alicemartinae n. sp. are its bipartite acrorhagi on the margin, uniform red colour, and marks from frequent longitudinal fission. Bud-like structures were observed in two specimens. Evidence of frequent fission and the absence of fertile males in the sample indicate a predominance of asexual reproduction in the population. The fact that such a conspicuous species was not reported in previous surveys of Chilean sea anemones suggests that it has been increasing in abundance and/or expanding its range during the last 50 years. Reasons for this may be human impact on benthic communities or recent introduction of this species into the area.

Key words: Actiniaria, Anemonia alicemartinae, Chile, benthos, biogeography, longitudinal fission.

electr. suppl.:   Part 1. Study sites Häussermann & Försterra. pdf-file, 130 KB
   Part 2. Study sites Sebens & Paine. pdf-file, 110 KB
   Part 3. Material examined. pdf-file, 110 KB
   Part 4. Figures

Fig. 1. Oral disc of A. alicemartinae with fission scar (Fs).

Fig. 2. Lateral view of A. alicemartinae.

Fig. 3. Margin of A. alicemartinae with pseudoacrorhagi (Pa) and small acrorhagi (Ac).

Fig. 4. Bud-like structure of A. alicemartinae:
a) view on oral disc
b) lateral view.

Fig. 5. Endodermal sphincter (Sp) of A. alicemartinae (azocarmine triple staining). Ac: acrorhagus; Ec: ectoderm; H: holotrichs; M: mesogloea.

Fig. 6. Transverse section of A. alicemartinae (azocarmine triple staining). Ap: lumen of actinopharynx; Ec: ectoderm; Im: pair of imperfect mesenteries; M: mesogloea; Mf: trilobate mesenterial filament; Pb: parietobasilar muscle; Pm: pair of perfect mesenteries; R: retractor; Si: siphonoglyph.

Fig. 7. Siphonoglyph (Si) with "reticulated pads" (Rp) of A. alicemartinae (eosin-hematoxilin staining). Ci: ciliae; M: mesogloea; Pm: pair of perfect mesenteries.

Fig. 8. A. alicemartinae (darker animals) in a typical habitat together with the sea anemone Anthothoe chilensis (white animals) and the sea urchin Tetrapygus niger.

Fig. 9. The extreme, lifeless Atacama Desert contrasts with the rich marine life along the north Chilean shore. With long distances between research facilities most of the examinations had to be done in a "field laboratory".

Fig. 10. Shore near Arica, north Chile (top), and at the southern distribution limit of A. alicemartinae near Concepción, central Chile (bottom). While the landscape changes dramatically along this range, conditions in the sea stay more or less constant. Strong wave action is typical throughout.

Fig. 11. Irregularities and regions with exceptionally short tentacles are a result of former fissions.

Fig. 12. Margin of a preserved specimen of A. alicemartinae: pseudoacrorhagi (Ps) and acrorhagi (Ac) in various developmental stages. Ob: oral branch carrying holotrichs.

Fig. 13. Longitudinal section of A. alicemartinae (azocarmine triple staining). Ac: acrorhagus; Bm: basilar muscle; Co: column; Me: mesenteries; Od: oral disc; Pd: pedal disc; T: tentacles.

Fig. 14. A. alicemartinae was regularly found between the rhizoids of the macroalgae Lessonia trabeculata.

Fig. 15. Even when emersed during extremely low tides, specimens of A. alicemartinae do not retract. The tentacles form a rim that retains water on the oral disc.


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