Brewed in the African pot: the phylogeography of the toothed barnacle Chthamalus dentatus (Chthamaloidea: Chthamalidae)

Figures & data

Figure 1. Chthamalus dentatus from Southern Africa. A. Young specimen from Port Elizabeth, South Africa. B. Eroded specimens from Mowe Bay, Namibia. C. Cylindrical specimen from Mowe Bay. D. Specimen from Port Elizabeth.

Figure 2. Chthamalus dentatus A. After Krauss (1848), Table VI Figure 27. B. After Darwin (1854), Plate XVIII Figure 3a. Shell. 3b. Attached to a ship's bottom, general view showing the dentate margins of shell plates. 3c. Tergum viewed from inside. C. After Nilsson-Cantell (1921), Page 293 Text Figure 52. D. After Stubbings (1967), Page 255 Figure 9f. Seta from the tip of cirrus II from a buoy at Bonny, Nigeria.

Figure 3. Map showing the 14 collection sites in Namibia, South Africa and Madagascar. The arrow points to the 15th site, Batoké in Cameroon, which is out off the map. Collection sites are coloured according to their clade identity (see Results): South African (blue), Namibian (red) and Cameroon (green).

Table I. Number of individuals (N) from each population. Coordinates are rounded to the nearest minute.

Population	Coordinates	N
Morondava, Madagascar	20°17′S 44°19′E	20
Durban, South Africa	29°53′S 31°03′E	24
Port Alfred, South Africa	33°36′S 26°54′E	11
Port Elizabeth, South Africa	33°57′S 25°36′E	19
Knysna, South Africa	34°03′S 23°03′E	30
Arniston, South Africa	34°40′S 20°14′E	20
Cape Agulhas, South Africa	34°49′S 20°01′E	29
Fish Hoek, South Africa	34°07′S 19°23′E	27
Camps Bay, South Africa	33°57′S 19°23′E	16
Kerbe Huk, Namibia	29°14′S 15°59′E	10
Elizabeth Bay, Namibia	26°55′S 15°11′E	2
Swakopmund, Namibia	22°41′S 14°32′E	21
Cape Cross, Namibia	21°47′S 14°00′E	23
Mowe Bay, Namibia	19°22′S 12°42′E	23
Batoké, Cameroon	04°02′N 09°06′E	13
Total		297

Figure 4. An UPGMA tree depicting the relationship between the 14 Chthamalus dentatus populations. (CMR = Cameroon, MDG = Madagascar, NAM = Namibia, and RSA = South Africa).

Table II. Mean genetic distances between the 14 sampled locations. The rightmost column displays the mean genetic distances within each location. Distances were calculated by the Kimura 2-parameter model.

	1	2	3	4	5	6	7	9	9	10	11	12	13	14		Within
1. Arniston																0.016
2. Cameroon	0.149															0.013
3. Camps Bay	0.016	0.150														0.012
4. Cape Agulhas	0.016	0.149	0.013													0.014
5. Cape Cross	0.060	0.149	0.063	0.062												0.014
6. Durban	0.021	0.146	0.021	0.021	0.052											0.023
7. Fish Hoek	0.017	0.147	0.015	0.016	0.059	0.021										0.017
9. Kerbe Huk	0.015	0.149	0.013	0.013	0.062	0.020	0.015									0.013
9. Knysna	0.015	0.149	0.013	0.014	0.062	0.021	0.016	0.013								0.014
10. Morondava	0.019	0.147	0.019	0.019	0.061	0.023	0.020	0.019	0.019							0.010
11. Mowe Bay	0.062	0.149	0.065	0.064	0.011	0.054	0.060	0.064	0.064	0.063						0.009
12. Port Alfred	0.016	0.144	0.013	0.014	0.061	0.020	0.016	0.014	0.014	0.019	0.063					0.014
13. Port Elizabeth	0.015	0.149	0.012	0.013	0.061	0.020	0.015	0.012	0.013	0.019	0.063	0.013				0.012
14. Swakopmund	0.063	0.149	0.065	0.064	0.012	0.054	0.060	0.064	0.064	0.063	0.009	0.063	0.063			0.011

Figure 5. The tri-modal distribution of all pairwise distances (with regard to the ABGD method).

Figure 6. A median-joining haplotype network. The three clades are Cameroon (CMR), Namibia (NAM) and South Africa (which is further divided into three sub-clades – RSA₁, RSA₂ and Madagascar).

Figure 7. A neighbor-joining tree of Chthamalus dentatus individuals from the Atlantic coast of Africa. Individuals are from Cameroon, Camps Bay (representing the South African populations), Swakopmund (representing the Namibian populations), Kerbe-Huk and Elizabeth Bay. The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (1000 replicates) is shown only if larger than 90%.

Table III. Mean genetic distances between the three Chthamalus dentatus and the four Chthamalus malayensis clades. Distances were calculated by the Kimura 2-parameter model.

	1	2	3	4	5	6	7
1. South Africa
2. Namibia	0.062
3. Cameroon	0.140	0.143
4. Christmas Island clade	0.196	0.199	0.163
5. Indo-Malay clade	0.154	0.153	0.130	0.127
6. South China Sea clade	0.172	0.193	0.166	0.070	0.121
7. Taiwan clade	0.137	0.144	0.130	0.125	0.094	0.113

Table IV. Mean genetic distance between the three Chthamalus dentatus clades and ten nominal species of Chthamalus. Distances were calculated by the Kimura 2-parameter model.

	1	2	3	4	5	6	7	9	9	10	11	12	13
1. South Africa
2. Namibia	0.061
3. Cameroon	0.149	0.149
4. C. alani	0.176	0.196	0.192
5. C. newmani	0.179	0.190	0.196	0.035
6. C. panamensis	0.196	0.197	0.201	0.090	0.096
7. C. fragilis	0.195	0.190	0.177	0.163	0.166	0.172
9. C. proteus	0.196	0.200	0.207	0.191	0.192	0.195	0.196
9. C. fissus	0.179	0.196	0.227	0.199	0.171	0.193	0.197	0.206
10. C. montagui	0.199	0.191	0.190	0.197	0.190	0.191	0.199	0.192	0.219
11. C. stellatus	0.191	0.191	0.170	0.193	0.197	0.197	0.179	0.192	0.206	0.139
12. C. dalli	0.199	0.199	0.160	0.169	0.166	0.164	0.166	0.176	0.200	0.150	0.165
13. C. challengeri	0.199	0.192	0.170	0.170	0.171	0.169	0.176	0.195	0.204	0.159	0.159	0.076

Figure 8. Photomicrographs of terminal segments of anterior rami of cirri II. A. Port Elizabeth, South Africa. B. Mowe Bay, Namibia. C. Morondava, Madagascar. D. Batoké, Cameroon.

Figure 9. SEM photograph of terminal segments of cirrus II and isolated seta. A. Serrulate setae on the terminal segment of posterior ramus of cirrus II of the specimen from Morondava, Madagascar. Guards on seta are indicated by arrows. B. Terminal segments with multi-cuspidate setae with guards of the specimen from Batoké, Cameroon. C. Isolated setae from Mowe Bay, Namibia. D. Isolated seta from the terminal segment of the specimen from Port Elizabeth, South Africa. E. Isolated setae from Morondava, Madagascar. F–I. Isolated setae from the specimens from Batoké, Cameroon.

Figure 10. Map showing the major current systems and upwelling systems in the southeast Atlantic Ocean and the southwest Indian Ocean. Redrawn according to the maps by Hardman-Mountford et al. (2003, ibid Figure 2) and by Lutjeharms and Bornman (2010, ibid Figure 1). Grey zones along the coasts represent upwelling cells.

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