Morphological and morphometric variability of the squid Lolliguncula brevis (Mollusca: Cephalopoda) in Brazilian waters: evidence for two species in the western atlantic?

Abstract

Morphological and morphometric variability of the small-sized coastal squid Lolliguncula brevis was assessed along the largest part of its latitudinal range in the southern hemisphere, off the Brazilian coast (8° S -27° S). A general homogeneity in form was found throughout the entire latitudinal range. In terms of body proportions, no latitudinal gradients were evident, but a few local "morphotypes" could be distinguished. The distinctive egg mass morphology, and size and form features, including a hectocotylus 20-40% longer than the opposing ventral arm and the presence of suckers on the buccal membrane, indicated that Lolliguncula from northern and southern hemispheres might comprise two different taxa.

Molecular Phylogeny of the Genus Lolliguncula Steenstrup, 1881 Based on Nuclear and Mitochondrial DNA Sequences Indicates Genetic Isolation of Populations from North and South Atlantic, and the Possible Presence of Further Cryptic Species

“…The divergence values observed between North and South Atlantic Lolliguncula brevis are of the same magnitude than the divergence values observed between other congeneric species. So, the genetic data is in perfect agreement to the proposal of Zaleski and colleagues [8] for the occurrence of distinct morphotypes within the range of Lolliguncula brevis. In this case, as the type locality of the species is Rio de Janeiro [23], Lolliguncula brevis would be the species name valid for the population from the South Atlantic.…”

“…The two species can be distinguished by the morphology of the males, and the shape of the fins in the females, as well as the fact that the two species are rarely captured together despite having a sympatric distribution [6]. Taxonomic uncertainties in relation to the subgenera Lolliguncula and Loliolopsis had been raised in previous studies due to their many shared morphological traits [4], [8], particularly similarities in the hectocotylus [4]. The results of the present study indicate that L. diomedeae lies within the Lolliguncula brevis - L. panamensis clade, making the Loliolopsis subgenus invalid.…”

“…In loliginid squid, genetic connectivity among populations may be influenced directly by either dispersal capacity of the planktonic larvae and/or mobility of the adults [6]. In comparison with other loliginids, Lolliguncula brevis has relatively large eggs and paralarvae, possibly indicating reduced dispersal [8]. Breakdown of widespread gene flow in Lolliguncula brevis may also be indicated from the identification of a number of local morphotypes by Zaleski [8], which may be related to reduced dispersal between inlets and estuaries in which populations of the species may become reproductively isolated along the southwest Atlantic coastline.…”

“…This was obtained through IBAMA (Brazilian Institute for the Environment and Natural Resources - license N° 12BR009032/DF). Specimens were handled following literature suggestions summarized in a review for aquaculture of cephalopods [13] and in a recent work with Cephalopods [5], [8]. Samples were obtained (already deceased) either from fishermen or, when collected alive they were anaesthetized and euthanased immediately following the 3R’s (replacement, reduction and refinement) concept and existing knowledge for cephalopods.…”

“…This species is found in relatively shallow waters, of less than 20 m in depth, and is tolerant of low salinity [2]. Studies conducted in the 1990s [7] indicated differences in the morphology and spawning patterns of Lolliguncula brevis populations in the northern and southern hemispheres, raising doubts with regard to the taxonomic validity of Lolliguncula brevis , in particular that specimens from the northern and southern Atlantic may represent distinct species [8].…”