Clathrina clathrus, (SCHMIDT, 1864)

Klautau, Michelle & Valentine, Clare, 2003, Revision of the genus Clathrina (Porifera, Calcarea), Zoological Journal of the Linnean Society 139 (1), pp. 1-62 : 17-18

CLATHRINA CLATHRUS ( SCHMIDT, 1864)

Original name: Grantia clathrus Schmidt, 1864

Type locality: Lesina, Adriatic Sea.

Type: Unregistered (syntype /alcohol), Schmidt specimen, ZMUC .

Citations: Gray (1867); Haeckel (1870, 1872); Vosmaer (1881); Lackschewitsch (1886); Priest (1887); Bianco (1888); von Lendenfeld (1891); Bidder (1891); Topsent (1894, 1934, 1936); Kirk (1896); Minchin (1896); Breitfuss (1896, 1898, 1935); Dendy & Row (1913); Ferrer-Hernandez (1916, 1918, 1922); Burton (1935, 1963); Borojevic (1968); Solé-Cava et al. (1991); Borojevic & Klautau (2000).

The specimen we received from ZMUC is a syntype of Ascetta (Clathrina) clathrus Schmidt, 1864 , collected in Lesina, Adriatic Sea. There are three large fragments of the specimen, preserved in alcohol. The largest is 2.5 ¥ 2.0 ¥ 0.5 cm .

Colour: Cormus of preserved specimen is brownishyellow.

Description: Cormus formed of large, irregular and loosely anastomosed tubes. It was not possible to recognize water-collecting tubes in the syntype. However, we analysed several other specimens from the Mediterranean Sea and the water-collecting tubes were always found.

The wall of the tubes is 102 Mm thick. The skeleton has no organization, comprising equiradiate and equiangular triactines only ( Fig. 12B). Actines are cylindrical, with rounded tips and they are undulated at their distal part.

Remarks: Clathrina clathrus ( Schmidt, 1864) is the type-species of the genus Clathrina Gray, 1867 . In his original description, Schmidt discussed the ‘beautiful sulphur yellow colour’ of specimens of this species, and said that if the colour was a constant character in C. clathrus , it would be easy to recognize it. As this species has only one type of spicule, it would be very useful to be able to use the colour as an effective character. Unfortunately, the colour is not an exclusive character, although it helps in identification.

Once authors began to report a high variation of colour (including white and red as well as yellow), its distribution, initially described from the Adriatic Sea (Lesina), started to increase. Burton (1963) listed occurrence of C. clathrus in the following localities: Mediterranean (Adriatic to Minorca); British Isles; Spain (Asturias); Ternate; New Zealand (Cook Strait) , in depths varying from 0 to 50 m.

It is not difficult to see that many of the specimens described for localities other than the Adriatic and the Mediterranean Seas were not in fact C. clathrus . The yellow colour of this species seems to be very constant, and because of this, some authors began, erroneously, to identify all yellow clathrinas as C. clathrus .

Allozyme analysis of specimens previously identified as C. clathrus from the Atlantic (Rio de Janeiro, Brazil) and the Mediterranean (Marseille, France) established that both populations were reproductively isolated and constituted distinct species. We have retained the name C. clathrus for the Mediterranean population. In addition to the molecular results, we also found differences in the size of the spicules, which are longer in the Mediterranean populations. Also, studying the morphology of some specimens of a yellow Clathrina from New Caledonia which has only triactines in its skeleton, we found differences in the thickness and tip of these actines, which was not rounded as in C. clathrus , but sharp. It was named C. chrysea Borojevic & Klautau, 2000 .

It is clear that the yellow clathrinas constitute a group of species which only have triactines in their skeleton. These triactines have cylindrical actines, undulated at the distal part, and are blunt or rounded at the tip.

Analysing all the specimens deposited at BMNH previously identified as C. clathrus , we again found some distinct species. We have already mentioned the importance of the shape of the actines in the genus Clathrina , and using this character to differentiate between species, we could distinguish three species in the collection. We considered those specimens with water-collecting tubes, yellow colour in life, and triactines with cylindrical actines, undulated at the distal part, and rounded at the tip as the true clathrus . Using these morphological characters, the distribution of C. clathrus is restricted to the Adriatic and the Mediterranean Seas.

We suggest that the specimen from ZMUC be considered the lectotype of C. clathrus .