SYSTEMATICS AND DISTRIBUTION OF THE FOUR SIBLING 

 SPECIES COMPRISING THE GENUS PONTELLINA DANA 



(COPEPODA, CALANOIDA) 



A. Fleminger and K. Hulsemann' 



ABSTRACT 



A global-scale study on systematics and distribution of the epipelagic copepod genus Pontel- 

 lina (Family Pontellidae) was carried out on materials sorted from about 2,000 zooplankton 

 samples collected at stations scattered throughout the circumglobal warm-water belt. Four 

 distinctive species were found and described, three being new to science. 



Each species was examined for evidence of conspicuous polytypy and geographical varia- 

 tion. Morphology and geographical distribution were utilized comparatively to perceive re- 

 lationships that would shed light on the nature of selection pressures operating on external 

 morphology. Morphology and distribution were also considered to determine phylogenetic 

 relationships within the genus. 



The geographic distribution of the four species was considered relative to major near-sur- 

 face hydrographic features characterizing tropical and subtropical latitudes and especially 

 the occurrence of eutrophic and oligotrophic areas in each ocean. 



Sets of similarly collected, quantitative samples were used to determine the relative abun- 

 dance of each species, and co-occurrences among the species were tested by recurrent group 

 analysis. The trophic role of each species was considered and conclusions tested by a limited 

 series of observations on stomach contents. 



Geographical perspective, too often absent 

 from studies on marine plankton, is a powerful 

 tool for dealing with sibling species. Evidence 

 of reproductively isolated populations that are 

 morphologically similar in planktonic calanoids 

 and other zooplankton as well has been present- 

 ed in a number of studies combining geograph-' 

 ical distribution and morphology (e.g., Schmaus, 

 1917; Johnson, 1935; Bowman, 1955, 1967; 

 Brodsky, 1959; Foxton, 1961; Jones, 1966; 

 Fontaine, 1967; Fleminger, 1967b; Frost and 

 Fleminger, 1968; Mullin, 1969; Jaschnov, 

 1970). Our resolution of the sibling species 

 comprising the genus Pontellina Dana is of- 

 fered as an additional example. 



In contrast to the 22 nominal species by our 

 count comprising Poiitellopsis Brady, the pontel- 

 lid genus most similar in morphology, P(>)itel- 

 lina has been universally regarded as monotypic 

 since Giesbrecht's (1892) monumental review 

 of planktonic marine copepods. Mori (1937) 

 presented evidence of polytypy in Pontellina 



' Scripps Institution of Oceanography, University of 

 California at San Diego, P.O. Box 1529, La Jolla, CA 92037. 



Manuscript accepted July 1973. 



FISHERY BULLETIN: VOL. 72, NO. 1, 1974. 



with his description of a unique male distin- 

 guished by an unusual chela. Apparently in- 

 fluenced by Sewell's views on copepod ontogeny 

 (1929, 1932), Mori ascribed the specimen 

 taken off Japan to pliunata, suggesting that it 

 represented the fully mature state and that 

 previous descriptions of the plumata male were 

 based on incompletely mature specimens. Our 

 study was prompted by the appearance of other 

 seemingly minor morphological features dis- 

 tinguishing adult individuals of both sexes that 

 correlated with indications of distinctive geo- 

 graphical distributions among the observed 

 forms. 



In this paper we redefine the genus and 

 describe its four species. The distribution of 

 each species is considered in the context of our 

 geographical records. Distribution is also dis- 

 cussed with respect to morphological similarities 

 among the species and relationships to general 

 oceanic circulation. Detailed considerations 

 and views regarding environmental conditions 

 that shape these distributions and the circum- 

 stances yielding the contemporary Pontellina 

 speciation pattern will be presented separately 

 elsewhere. 



63 



