Gill raker structure and development in indo‐pacific anchovies (Teleostei: Engrauloidea), with a discussion of the structural evolution of engrauloid gill rakers

Abstract

The postlarval development of gill raker denticles is described for the engrauloid (anchovy) genera Coilia, Lycothrissa, Setipinna, Thryssa, Stolephorus, and Encrasicholina based on scanning electron microscopy. The raker structure of adult Papuengraulis is also described. In the coiliid genera Coilia, Lycothrissa, Setipinna, Thryssa, and Papuengraulis, denticle development is not confined to particular region(s) of the raker. With few exceptions, the proliferation of denticles with growth is greatest along the upper raker edge; denticles are smaller and less dense on the raker faces and along the lower raker edge. Some Thryssa and Setipinna have a derived condition of denticle clustering along the upper raker edge. In Stolephorus and Encrasicholina, denticle development is confined to the upper raker half and includes the development of a single row of denticles along each raker face. A phylogenetic analysis of engrauloid raker structure, incorporating data from Bornbusch ( 88: Copeia 1988:174-182) and based on outgroup comparisons, indicates that for the Engrauloidea: (1) the pattern of denticle development shared by coiliids is plesiomorphic; and (2) the pattern of denticle development shared by Stolephorus, Encrasicholina, and most other engraulids is synapomorphic for the Engraulidae. There is no evidence that the studied coiliids Stolephorus and Encrasicholina are suspension feeders. The engraulid pattern of raker denticle development which is retained in suspension feeding engraulids of the genus Engraulis was thus derived before the derivation of suspension feeding in Engraulis. Comparative morphological and phylogenetic studies of clupeomorph raker structures and feeding behaviors can infer the historical origins of morphology-behavior associations, help define possible directions for analyses of raker denticle function, and thereby help elucidate the significance of structure-function couplings in the evolution of such clupeomorph trophic behaviors as suspension feeding. © 1992 Wiley-Liss, Inc.

Molecular systematics of the anchovy genus Encrasicholina in the Northwest Pacific

“…The ML analysis yielded a fully resolved phylogenetic tree with most of the relationships strongly supported by high bootstrap proportions (BPs) ( Fig 1 ). In this tree, the family Engraulidae was divided into two clades corresponding to the two subfamilies Coiliinae and Engraulinae (BPs = 100%); this is congruent with the results of several morphological and molecular studies [ 6 , 8 , 19 , 20 , 22 ]. The Coiliinae comprises the sampled IWP genera Coilia , Thryssa , Lycothrissa , and Setipinna , whereas the Engraulinae includes the IWP genera Stolephorus and Encrasicholina along with the "New World anchovy" clade representative genera Lycengraulis , Amazonsprattus , Anchoviella , and Engraulis .…”

“…In the large tropical Indo-West Pacific (IWP) biogeographical region, inclusive of Hawaii Archipelago and Polynesia [ 1 ], endemic anchovies (Engraulidae; Clupeoidei) comprise about 50 species currently classified in seven genera: Coilia , Encrasicholina , Lycothrissa , Papuengraulis , Setipinna , Stolephorus , and Thryssa [ 2 – 5 ]. These seven genera do not form a monophyletic group because two of them, Stolephorus and Encrasicholina , were hypothesized to be more closely related to the "New World anchovy" clade than to other IWP genera [ 6 – 8 ]. New World anchovies (including Engraulis ) along with Stolephorus and Encrasicholina make up the subfamily Engraulinae, whereas the other five IWP genera make up the subfamily Coiliinae [ 3 , 6 ].…”

Chirocentrids as engrauloids: evidence from suspensorium, branchial arches, and infraorbital bones (Clupeomorpha, Teleostei)

“…Ceratobranchials 1 and 2 of selective planktivorous engraulids, such as Anchoviella lepidentostole , which feed on larvae and small crustaceans (Cervigón, 1982; Bornbusch, 1988), are covered by reduced but sequentially aligned autogenous tooth plates. That same arrangement and a similar degree of development of tooth plates is also present on ceratobranchials 1 and 2 of examined Stolephorus , which feed mostly on selected small crustaceans or large zooplankton, such as amphipods, copepods, mysids, ostracods, brachyuran larvae, and euphasiids (Hardenberg, 1934; Blaber, 1979; Milton, Blaber & Rawlinson, 1990; Bornbusch & Lee, 1992). Stolephorus is hypothesized to be the most basal genus of the Engraulidae (Grande & Nelson, 1985).…”

“…Hypothesized synapomorphies of the Engrauloidea are the mesethmoid projecting anteriorly beyond the vomer and the oblique inclination of the suspensorium (Nelson, 1984; Grande & Nelson, 1985; Grande, 1985). The Engrauloidea is divided into the Coiliidae and Engraulidae (Grande & Nelson, 1985; Bornbusch & Lee, 1992; Li & Ortí, 2007). Apart from the division of the superfamily into those two families, relationships among anchovies are largely unknown.…”

Bottles as models: predicting the effects of varying swimming speed and morphology on size selectivity and filtering efficiency in fishes

“…In teleosts, the gill raker structures generally vary by the length of the rakers and their spacing (Nelson, 1967;Bertmar and Strömberg, 1969;Gibson, 1988;Bornbusch and Lee, 1992;van den Berg et al, 1994;Kumari et al, 2005;Friedland et al, 2006;Vigliano et al, 2006). However, the gill raker structures (sometimes referred to as filtering pads) of the filtering cartilaginous fishes exhibit substantial interspecific variation.…”