The shrimp superfamily Sergestoidea: a global phylogeny with definition of new families and an assessment of the pathways into principal biotopes

Abstract

The phylogenetic analysis of Sergestoidea based on 253 morphological characters and encompassing all 99 valid species confirmed all previously recognized genus-level clades. Analysis retrieved five major robust clades that correspond to families Luciferidae, Sergestidae, Acetidae fam.n., Sicyonellidae fam.n. and Petalidiumidae fam.n. Synonymy, emended diagnoses and composition of revealed family-level clades are provided. Three types of morphological characters were important in the phylogeny of the Sergestoidea: general external characters, copulatory organs, and photophores. Novel metrics to quantify the contribution of these character types were tested. General external characters were significant in supporting the major clades (80% of the families and nearly half of the genera). Copulatory organ characters and photophores greatly supported the medium-level clades: Lucifer, Belzebub, Petalidium, Neosergestes, Challengerosergia (copulatory organ characters) and Lucensosergia, Challengerosergia, Gardinerosergia, Phorcosergia (photophores). An evolutionary model of the Sergestoidea showing their pathways into their principal biotopes is proposed: the major clades evolved in a vertical direction (from epi- to bathypelagic); further divergence at the genus level occurred within vertical zones in a horizontal direction, with the invasion of the benthopelagic and neritic (shelf and estuarine) habitats and speciation within these domains.

A phylogenomic framework, evolutionary timeline and genomic resources for comparative studies of decapod crustaceans

“…Dendrobranchiate relationships are consistent (figure 2), except the aforementioned long-branch attraction of Lucifer to outgroups. Amino acid results place this perplexing decapod with Sergestidae (pelagic shrimp), as suggested by morphological analysis, especially spermatophore morphology [43]. Crown dendrobranchiates diverged in the Late Devonian (figure 3), with the two main clades Sergestoidea and Penaeoidea both diverging in the Pennsylvanian (approx.…”

A phylogenetic study of krill (Crustacea: Euphausiacea) reveals new taxa and co‐evolution of morphological characters

“…Co‐evolution was observed only in five genera of Euphausiacea ( Nematobrachion , Thysanopoda , Euphausia , Pseudeuphausia and Meganycthyphanes ) that suggests a genus‐specific mechanism of the “probe” stage. It is noteworthy that similar structures on the antennular peduncle of the sergestid shrimps (the “clasping organ”) are also genus‐dependent: they are synapomorphic for Challengerosegia and Lucensosergia and absent in other genera (Vereshchaka, ).…”

The genus Gennadas (Benthesicymidae: Decapoda): morphology of copulatory characters, phylogeny and coevolution of genital structures

“…However, genital structures (female thelyca and male petasmata) show an outstanding diversity in Gennadas and are therefore promising for phylogenetic reconstruction as was shown for other Dendrobranchiata [11][12][13][14]. Despite a greatly elaborate morphology, structural variation in the thelyca and petasmata between specimens are well known to be negligible, so these organs have traditionally been used as 'fingerprints' for species identification [3,5,10].…”