Notes on several species of the Chamidae by M.C. van Veen, April 2020 Introduction Most species of the family Chamidae have been described during the 18th and 19th century, in an era when photography was absent or still in its infancy. The conchological books of the time show drawings, which are often confusing because of the intraspecific variability of Chamidae species. Currently the World Register of Marine Species (WoRMS) lists 39 species of the genus Chama, with an additional 96 synonyms, and also 28 descriptions that are classified as 'nomen dubium'. So in total there are more than three times as many unacknowledged descriptions than valid species, a very high number. Of the genus Pseudochama currently 16 species have been recognised, and 9 additional descriptions have been regarded as synonyms. In this article the taxons of three species are highlighted: Pseudochama cristella (Lamarck, 1819), the 'nomen dubium' Chama fragum Reeve, 1847, and Chama fimbriata Reeve, 1846 non Defrance. Pseudochama cristella (Lamarck, 1819) In Conchologia Iconica Volume 4 (1847) Reeve mentioned this species no less than five times, and this indicates how confusing the intraspecific variability can be. The illustration below shows Reeve's number 19: Chama radians, number 21: Chama ferruginea, number 42: Chama cristella, number 50: Chama variegata, amd number 55: Chama appressa. Figure 1. drawings of Pseudochama cristella (Lamarck, 1819) in Reeve's Conchologia Iconica. Reeve mentioned that three of these five numbers came from Honduras (the Caribbean side), except for Chama radians and Chama cristella, both described by Lamarck in 1819. Lamarck introduced both Chama radians and Chama cristella in his 'Histoire naturelle des animaux sans vertèbres' (tome 6) and mentioned "l'Océan des grandes Indes", The Ocean of the Great Indies, as the distribution range. Reeve mentioned Batavia as the origin of Chama cristella. Reeve's depiction of Chama cristella (number 42 in Figure 1) resembles Pseudochama retroversa (Lischke, 1870) very much, which was described from Japan but is also known from Taiwan (see Figure 2). Figure 2. Pseudochama retroversa (Lischke, 1870). Taiwan, in 1972. length: both 27 mm. Note the white patch on the upper valve, similar to Reeve's number 42 in Figure 1. Clessin (1889) recognised that Reeve's Chama cristella was different. He named it Chama reeveana instead (Figure 3), and not only mentioned Reeve's locality, Batavia, but also The Moluccas. Figure 3. Chama reeveana Clessin, 1889. However, Clessin's Chama reeveana had already been described by Chenu in 1846 as Chama subspinosa (Figure 4). Figure 4. Chama subspinosa, nowadays known as Pseudochama subspinosa (Chenu, 1846) Pseudochama subspinosa seems very similar to Pseudochama retroversa (Lischke, 1870), even though both Reeve and Clessin mentioned Indonesia as the country of origin. Currently, Pseudochama retroversa is only known from Japan and Taiwan. Huber (2010) mentions that Chenu also provided a depiction of Lamarck's holotype of Chama cristella (Figure 5), which resides in the Natural History Museum of Geneva. Figure 5. Chama cristella (Lamarck, 1819). Holotype. Figure 6. Pseudochama cristella (Lamarck, 1819). Panama northwest, Bastimentos Island, in 2007. Maximum dimension specimens: 40 mm and 50 mm. Figure 7. Pseudochama cristella (Lamarck, 1819). USA, Florida, Clearwater, old Dunedin Pass, in 1973. Maximum dimension specimens: 48 mm and 60 mm. To clarify the change into Pseudochama: the 'sinistral type' of Chama is nowadays classified as genus Pseudochama; hence the taxon is known today as Pseudochama cristella (Lamarck, 1819). Chama fragum Reeve, 1847 - nomen dubium? Reeve introduced this species in his Conchologia Iconica (1847) Reeve's very basic description is as follows: The Strawberry Chama - Shell somewhat orbicular, upper valve concentrically very finely fimbriately laminated, laminae somewhat tubulous toward the margin, lower valve rudely tubulously squamate, margins of the valves minutely crenulated; white, dotted with red, interior whitish. Hab. Island of Mindoro, Philippines. Abrard (1941) mentioned nine fossil Pleistocene valves from Djibouti, which now reside in the Muséum National d'Histoire Naturelle in Paris. One of these valves can be viewed here: https://science.mnhn.fr/institution/mnhn/collection/f/item/a26871 Figure 8. Chama fragum Reeve, 1847. On the left the picture Reeve (1847) provided, on the right the pictures Clessin (1889) provided of the species. The possible syntypes currently reside in the Natural History Museum in London, but Huber (2010) remarks that these specimens do not match Reeve's description. Below photographs of specimens from my personal collection (Figure 9 to 14) Figure 9 (previous page) 1. Chama fragum Reeve, 1847. length: 30 mm. Unknown locality. Before 1985. 2. Chama fragum Reeve, 1847. length: 29 mm. Japan, Kii Peninsula, in 1973. 3. Chama fragum Reeve, 1847. length: 28 mm. Japan, Kii Peninsula, in 1973. 4. Chama fragum Reeve, 1847. length: 27 mm. Japan, Kii Peninsula, in 1973. Noteworthy is the double row of spikes which radiates from the posterior, even though in some specimens this is only a rudimentary feature, like in Clessin's depiction (Figure 8, right). Also, the inside of the upper (right) valve has got a reddish colouration posteriorly. P. Ovalis and A. Zenetos published an article in 2007 about the establishment of two alien species in the eastern Mediterranean, which were according to them Chama aspersa Reeve, 1846 and Chama asperella Lamarck, 1819. Their Chama aspersa seems to be Chama fragum instead. One interesting question is whether or not this invasive species originates from Japan just like the Arcid bivalve Anadara kagoshimensis Tokunaga 1906, which is also an invasive species in the Mediterranean. Figure 10. Chama fragum Reeve, 1847. length: 30 mm. Unknown locality. Before 1985. Figure 11. Chama fragum Reeve, 1847. length: 29 mm. Japan, Kii Peninsula, in 1973. Figure 12. Chama fragum Reeve, 1847. length: 28 mm. Japan, Kii Peninsula, in 1973. Figure 13. Chama fragum Reeve, 1847. length: 27 mm. Japan, Kii Peninsula, in 1973. Figure 14. Chama fragum Reeve, 1847. Cluster of two specimens. Length 20 mm and 26 mm. Japan, Kii Peninsula, in 1973. A species that looks similar to Chama fragum is Chama limbula Lamarck, 1819, at least the juvenile specimens have some resemblance. Figure 15. Species number 17 in Conchologia Iconica is Chama nivalis Reeve, 1846, which is synonym to Chama limbula. Figure 16. Chama limbula Lamarck, 1819. Maximum dimension 36 mm. The shell is attached to Anadara antiquata (Linnaeus, 1758). length: 51 mm. Philippines, Daanbantayan. At 8 to 15 m depth, in 2009. Figure 17. Two adult specimens of Chama limbula Lamarck, 1819. Left: maximum dimension 47 mm. Thailand, Phuket Island, in 1974. Right: maximum dimension 57 mm. Eritrea, near Disei Island. At 2 m depth, in 1974. Chama fimbriata Reeve, 1847 non Defrance Defrance introduced Chama fimbriata in 1817, and photographs of this fossil species can be found in Cossmann & Pissarro (1905). Reeve published his own Chama fimbriata in 1847, number 41 in Conchologia Iconica. Figure 18. Chama fimbriata Reeve, 1847 non Defrance. WoRMS hasn't updated this entry since 2010, and still lists Chama fimbriata Reeve, 1847 as synonym to Chama ruderalis Lamarck, 1819. Maybe it was synonymised this way because Chama ruderalis is an Australian species just like Reeve's Chama fimbriata: Reeve mentioned that his specimen originated from Point Cunningham, North Australia. But Reeve's number 41 depicts a sinistral specimen, so it is not at all similar to Chama ruderalis, which only occurs in the southern half of Australia as well. Most likely Reeve's depiction shows Cleidothaerus albidus (Lamarck, 1819), not a member of the Chamidae but of the family Cleidothaeridae. Chenu (1842-1854) shows a clear picture of this species (Figure 19), even though he erroneously assigned it to Sowerby. Figure 19. Chenu's depiction of Cleidothaerus albidus (Lamarck, 1819). Figure 20. Cleidothaerus albidus (Lamarck, 1819). maximum dimension 42 mm. Locality: Australia, Northern Territory, Darwin, Mindil Beach. Personal collection. Literature next page. References Abrard, R., 1941. Archives du Muséum national d'histoire naturelle, Series 6, Tome 18. Mollusques Pléistocènes de la Côte Française des Somalis. Plate 3. Chemnitz, J.H., 1786. Neues systematisches Conchylien-Cabinet, Band 9, Abteilung 1, plate 116. Chenu, J.C., 1842-1854. Illustrations conchyliologiques, ou description et figures de toutes les coquilles connues vivantes et fossiles. Clessin, S., 1889. Systematisches Conchylien-Cabinet, Band 8, Abteilung 5, Chamiden, page 22 & 38, plate 10 & 16. Cossmann, M., & Pissarro, G., 1905. Iconographie complète des coquilles fossiles de l'Éocène des environs de Paris, Tome 1, plate 20-21. Huber, M., 2010. Compendium of Bivalves, volume 1, chapter 6. Lamarck, J.B.P., 1819. Histoire naturelle des animaux sans vertèbres, Tome 6, page 96. Lischke, C.E., 1871. Japanische Meeres-Conchylien, Book 2, page 131, plate 9. Ovalis, P. & Zenetos, A., 2007. Mediterranean Marine Science, Volume 8/2, page 97-100. On the establishment of two more (Chama aspersa Reeve, 1846 and Chama asperella Lamarck, 1819) alien mollusca in the eastern Mediterranean. Reeve, L.A., 1847. Conchologia iconica, Volume 4, Monograph of the genus Chama..