OBSERVATIONS ON CHAETOCEROS BUCEROS (BACILLARIOPHYCEAE), A RARE TROPICAL PLANKTONIC SPECIES COLLECTED FROM THE MEXICAN PACIFIC¹

Abstract

Examination of net plankton samples from the Gulf of Tehuantepec (Mexican Pacific) yielded a rare tropical species of the genus Chaetoceros, C. buceros Karsten. This species is conspicuous because of its relatively large size, type of chain formation, and shape of the terminal setae. Electron microscopic study revealed other interesting characteristics: the intercalary values are more lightly silicified than the terminal valves and show a pattern of costae radiating form the center with various annuli (“central hyaline fields”) in the center of the valve face; both kind of valves are perforated by small poroids. Terminal valves possess several (21–30) slitlike and randomly oriented rimoportulae. Important morphological differences exist between the intercalary and the terminal setae. Morphological characters, comparision with related species, and the systematic position are discussed. A new section of the subgenus Hyalochaete, Conspicua, is proposed to include C. buceros.

Systematics of Chaetocerotaceae (Bacillariophyceae). I. A phylogenetic analysis of the family

“…Species from these areas have been forced into the intellectual framework of our North Atlantic-based classification schemes, instead of leading to a critical re-evaluation of the traditional system. In spite of the careful work of Hernández-Becerril (1989, 1991a,b,c, 1992, 1993a,b, 1996 and Hernández-Becerril et al (1993), the tropical flora contains numerous undescribed species (J. E. B. Rines, unpublished observations). Although many Chaetoceros are known from austral seas (Karsten 1905;Mangin 1915;Heiden & Kolbe 1928;Manguin 1960;Hargraves 1968), virtually none of them have been studied live, or with electron microscopy in sufficient detail to code character states for our data matrix.…”

Chaetoceros phuketensissp. nov. (Bacillariophyceae): a new species from the Andaman Sea

“…buceros (Fig. 7, and Hernández-Becerril et al 1993). We were unable to fully interpret this structure.…”

“…Large numbers of processes were first documented by Hernández-Becerril (1991a, 1991b in Chaetoceros bermejensis Hernández-Becerril (s.g. Hyalochaete) and Ch. coarctatus (s.g. Phaeoceros), and by Hernández-Becerril et al (1993) in Ch. buceros.…”

“…Lauder 1864; Cleve 1873; Ikari 1926Ikari , 1928Steemann Nielsen 1931). Several recent studies have begun to examine the Chaetoceros of Mexican and Caribbean waters (Hernández-Becerril 1991a;1991b;1992a;1992b;1993a;1993b, 1996, 1998Hernández-Becerril et al 1993;Rines and Boonruang 1995). Their major findings have been that: (i) taxa originally known only from the Indo-West Pacific may also be found in the American tropics; (ii) there are numerous tropical taxa presently unknown to science; and (iii) tropical taxa have a variety of ultrastructural features unknown in temperate taxa, and thus they are poorly accommodated in Gran and Ostenfeld's traditional classification scheme (Gran 1897;Ostenfeld 1903).…”

“…Comparison of the characteristics of the Chaetoceros phuketensis sp. nov., Chaetoceros bermejensis Hernández-Becerril and Chaetoceros buceros Karsten Hernández-Becerril 1991a, bKarsten 1907, c Hendey 1937, d Hernández-Becerril et al 1993. ND, not determined.…”