Caulerpa brachypus Harvey, 1860: 333

Coppejans, Eric, Leliaert, Frederik, Verbruggen, Heroen, de Clerck, Olivier, Schils, Tom, de Vriese, Thomas & Marie, Daniel, 2004, The marine green and brown algae of Rodrigues (Mauritius, Indian Ocean), Journal of Natural History 38 (23), pp. 2959-3020 : 2979

* Caulerpa brachypus Harvey, 1860: 333

( figures 7–13 ) References: Weber-van Bosse, 1898: 282–283, pl. 22, figures 3, 4 ; Jaasund, 1976: 19,

figure 39; Coppejans and Prud’homme van Reine, 1992: 673, figures 1A–C , 7A ;

Trono, 1997: 30, figure 17 ; Littler and Littler, 2000: 358, figure p. 359.

Type locality. Tanega-shima , Kogashima Prefecture, Japan .

Vouchers. HEC 14612, 18 September 2001, western side of Cotton Bay (s.s. 13) ; HEC 14656a , HEC 14656b (zF), 19 September 2001, Gravier (s.s. 16) ; HEC 14718, 21 September 2001, Petite Butte (s.s. 24) ; HEC 14769, 25 September 2001, Passe Grand Bassin (s.s. 2) ; HEC 14867, 30 September 2001, south-western part of the lagoon (s.s. 31) .

Ecology. In pools of the mid- to low intertidal zone and in the subtidal; on silty-sandy substrate as well as on coral rubble or even coral heads, locally even in very turbid water and covered by silt.

Distribution. Aldabra Islands, Indonesia, Madagascar, Mauritius ( Børgesen, 1946: 36–37, figures 14, 15 ; 1948: 31–32 ( C. brachypus var. mauritiana ); 1951: 8–9, figure 3 ( C. brachypus var. mauritiana f. exposita )), Mozambique, Rodrigues (this paper), Seychelles, Somalia, South Africa, Tanzania.

Note. This is the most frequent Caulerpa species on Rodrigues, forming dense meadows over vast surfaces in different biotopes. Fishermen use it as bait and it is heavily collected for that purpose. Its morphology is variable in size and in branching pattern. The assimilators are rather fleshy. Most collections have simple (or only rarely branched) assimilators that are plain with smooth margins, approximately 5 cm high. In other populations the blades are very large (up to 20–25 cm long), repeatedly dichotomously branched, with (partly) dentate margin. In these specimens, secondary stolons are formed higher up. All intermediates between those two forms occur. At Pointe Palmiste the large growth form develops in grooves between bumps of coral rubble, the small growth form is present on the bumps, just under mean low water mark (most probably exposed at spring low tide). In one collection the apical parts of the assimilators are three-winged and dentate, the lower portion being plain and strap-like.

Figures

FIGS 7–13. Caulerpa brachypus, variation in the general morphology and margin structure of the assimilators. (7) Large growth form collected in grooves between bumps of coral rubble, frequently branching and with secondary stolons (HEC 14867). (8) Intermediately large growth form with wide assimilators (HEC 14769). (9) Intermediately large growth form with relatively narrow assimilators (HEC 14656a). (10) Typical specimen with simple or scarcely branched assimilators (HEC 14612). (11) Assimilator with smooth margin (HEC 14612). (12) Assimilator with coarsely dentate margin (HEC 14656a). (13) Assimilator with densely dentate margin (HEC 14718). Scale bars: 2 cm (7–10); 1 mm (11–13).

FIGS 2–6. Chlorophyta. (2) Microdictyon tenuius, detail of branching and anastomosing patterns (HEC 14849). (3) Bryopsis pennata var. pennata, branchlets of last order contiguous and in a single plane (HEC 14796 p.p.). (4) Bryopsis pennata var. leprieurii, branchlets of last order interrupted and in a single plane (HEC 14757).(5) Bryopsis pennata var. secunda, branchlets of last order curved in one direction (HEC 14796 p.p.). (6) Chamaedoris delphinii (HEC 14617). Scale bars: 250 mm (2); 5 mm (3–5); 1 cm (6).

FIG. 1. Sampling stations. See table 1 for a list of the stations and their GPS coordinates. Map redrawn from Wells (1988). The outer grey line represents the fringing reef.

FIGS 14–18. Caulerpa. (14) Caulerpa cupressoides var. lycopodium f. elegans, small, elegant specimen (HEC 14691). (15) Caulerpa cupressoides var. lycopodium f. elegans, coarse specimen with richly branched assimilators (HEC 14820). (16) Caulerpa sertularioides f. sertularioides, last order branchlets in a single plane (HEC 14739). (17) Caulerpa sertularioides f. farlowii, last order branchlets in several planes (HEC 14690). (18) Caulerpa webbiana (HEC 14699). Scale bars: 1 cm.