Cédric d'Udekem d'Acoz

Is the Species Flock Concept Operational? The Antarctic Shelf Case

There has been a significant body of literature on species flock definition but not so much about practical means to appraise them. We here apply the five criteria of Eastman and McCune for detecting species flocks in four taxonomic components of the benthic fauna of the Antarctic shelf: teleost fishes, crinoids (feather stars), echinoids (sea urchins) and crustacean arthropods. Practical limitations led us to prioritize the three historical criteria (endemicity, monophyly, species richness) over the two ecological ones (ecological diversity and habitat dominance). We propose a new protocol which includes an iterative fine-tuning of the monophyly and endemicity criteria in order to discover unsuspected flocks. As a result nine « full » species flocks (fulfilling the five criteria) are briefly described. Eight other flocks fit the three historical criteria but need to be further investigated from the ecological point of view (here called « core flocks »). The approach also shows that some candidate taxonomic components are no species flocks at all. The present study contradicts the paradigm that marine species flocks are rare. The hypothesis according to which the Antarctic shelf acts as a species flocks generator is supported, and the approach indicates paths for further ecological studies and may serve as a starting point to investigate the processes leading to flock-like patterning of biodiversity.

Redescription of Hippolyte Obliquimanus Dana, 1852, and Comparison With Hippolyte Williamsi Schmitt, 1924 (Decapoda, Caridea)

Examination of topotypic (Brazilian) specimens of Hippolyte obliquimanus Dana, 1852, and H. exilirostratus Dana, 1852, shows that the two species are identical and also conspecific with the West Indian H. curacaoensis Schmitt, 1924. The name obliquimanus Dana, 1852 is given precedence over exilirostratus Dana, 1852. The species is redescribed and compared to its East-Pacific counterpart H. williamsi Schmitt, 1924.

On Liljeborgia fissicornis (M. Sars, 1858) and three related new species from Scandinavia, with a hypothesis on the origin of the group fissicornis

The large and common Scandinavian amphipod Liljeborgia fissicornis (M. Sars) is split into four species: the deep-water L. caliginis sp. nov. and L. charybdis sp. nov., and the shallow-water L. fissicornis and L. ossiani sp. nov. The poorly known species L. polosi Barnard and Karaman, recorded from the deep Canadian Basin of the Arctic Ocean, is considered as belonging to the same group. All those northern species are completely devoid of eyes, while similar species from the Antarctic and sub-Antarctic continental shelf do have eyes. It is hypothesized that the group fissicornis, which is specific to cold waters, derives from ancestors living on the continental shelf of the Southern Ocean. These ancestors would have adapted to deep-sea environments, losing their eyes completely. Then they would have migrated northwards through the cold abyss, and reached the cold but shallow waters of the Arctic/sub-Arctic continental shelf, without redeveloping visual organs.

Images are not and should not ever be type specimens: a rebuttal to Garraffoni & Freitas

Note. This original form of this rebuttal was submitted to Science on 3 March 2017 (limited to 300 words as per Science editorial policy) but rejected on 13 March 2017. Herein, we elaborate on our original Science submission in order to more fully address the issue without the length limitations. This rebuttal is followed by the list of the signatories who supported our original submission.

Locked in the icehouse: Evolution of an endemic Epimeria (Amphipoda, Crustacea) species flock on the Antarctic shelf

The Antarctic shelfs marine biodiversity has been greatly influenced by the climatic and glacial history of the region. Extreme temperature changes led to the extinction of some lineages, while others adapted and flourished. The amphipod genus Epimeria is an example of the latter, being particularly diverse in the Antarctic region. By reconstructing a time-calibrated phylogeny based on mitochondrial (COI) and nuclear (28S and H3) markers and including Epimeria species from all oceans, this study provides a temporal and geographical framework for the evolution of Antarctic Epimeria. The monophyly of this genus is not supported by Bayesian Inference, as Antarctic and non-Antarctic Epimeria form two distinct well-supported clades, with Antarctic Epimeria being a sister clade to two stilipedid species. The monophyly of Antarctic Epimeria suggests that this clade evolved in isolation since its origin. While the precise timing of this origin remains unclear, it is inferred that the Antarctic lineage arose from a late Gondwanan ancestor and hence did not colonize the Antarctic region after the continent broke apart from the other fragments of Gondwanaland. The initial diversification of the clade occurred 38.04Ma (95% HPD [48.46Ma; 28.36Ma]) in a cooling environment. Adaptation to cold waters, along with the extinction of cold-intolerant taxa and resulting ecological opportunities, likely led to the successful diversification of Epimeria on the Antarctic shelf. However, there was neither evidence of a rapid lineage diversification early in the clades history, nor of any shifts in diversification rates induced by glacial cycles. This suggests that a high turnover rate on the repeatedly scoured Antarctic shelf could have masked potential signals of diversification bursts.

New records of West and South African Bathyporeia, with the description of four new species and a key to all species of the genus (Crustacea, Amphipoda)

New data on the warm temperate and tropical east Atlantic Bathyporeia species are presented. Four new species are described: Bathyporeia cunctator sp. nov. from South Africa, B. chevreuxi sp. nov. from Senegal, B. gladiura sp. nov. from South Africa, and B. griffithsi sp. nov. from Namibia. Bathyporeia cunctator sp. nov. and B. chevreuxi sp. nov. are very closely related to the west European B. tenuipes Meinert, 1877 and the Mediterranean B. lindstromi Stebbing, 1906; these four cryptic species forming the complex tenuipes. Bathyporeia griffithsi sp. nov. and B. gladiura sp. nov. are highly distinctive new species. The morphotype “sunnivae” of Bathyporeia guilliamsoniana is recorded for the first time outside the Mediterranean Sea, in the Canary Islands. An identification key to all known Bathyporeia species is given.

DNA analyses reveal abundant homoplasy in taxonomically important morphological characters of Eusiroidea (Crustacea,Amphipoda)

Eusiroidea is one of the 20 amphipod superfamilies that were erected to subdivide the very large and controversial suborder Gammaridea. Yet, the definition of the superfamily is not based on synapomorphies, but on a combination of diagnostic phenetic similarities that hold more or less consistently across families. Moreover, many of the characters used to define eusiroid families are suspected to show convergent evolution. The current classification of the Eusiroidea may therefore not reflect evolutionary relationships accurately. Here, we present a molecular phylogenetic re‐analysis of the Eusiroidea based on a comparison of 18S and 28S rDNA sequences of 73 species, representing 47 genera and 16 families that potentially belong to the superfamily. The results suggest that at least species belonging to 14 of these traditional families would be part of a eusiroid clade, increasing by more than twofold the species and generic richness of the group. However, most of the eusiroid families surveyed do not appear monophyletic. Finally, the analyses show that several important morphological characteristics, traditionally used in eusiroid taxonomy, are homoplastic.

The genus Liljeborgia in the Mediterranean Sea, with the description of a new species (Crustacea: Amphipoda: Liljeborgiidae)

A new amphipod crustacean, Liljeborgia clytaemnestra sp. nov., is described based on specimens from Malta and the Bay of Naples. It is quite similar to the sympatric L. dellavallei Stebbing, 1906, but it has narrower and more regular-sized spines on the propodus of pereiopods 3–4. The longest spine on the dorsolateral border of the peduncle of uropod 1 is not strongly elongate in adult males, as in L. dellavallei. The apical spines on the lobes of the telson are much longer than in L. dellavallei. L. clytaemnestra sp. nov. is actually more similar to two northeastern Atlantic species, the British L. pallida (Spence Bate, 1857) and the Scandinavian L. brevicornis (Bruzelius, 1859) than to the Mediterranean L. dellavallei. In L. clytaemnestra sp. nov., article 2 of the mandibular palp has setae on distal third, whilst setae are restricted to tip in the two other species. Article 3 of the mandibular palp is also longer in L. clytaemnestra sp. nov. than in the two Atlantic species. The spines of the outer plate of the maxilliped are longer in L. clytaemnestra sp. nov. than in the two other species. The most distal spine of the propodus of pereiopods 3–4 is reduced in L. clytaemnestra sp. nov. and L. brevicornis, but not in L. pallida. The serration of the posterior border of the basis of pereiopod 7 is much stronger in L. clytaemnestra sp. nov. than in the two other species. Finally, in L. clytaemnestra sp. nov., the spines of the lobes of the telson are longer than in L. pallida. A lectotype is designated for L. dellavallei. The presence/absence of a posterodorsal tooth on pleonite 3 in L. dellavallei is discussed. The validity of L. kinahani (Spence Bate, 1862) is questioned. An identification key is proposed for Mediterranean Liljeborgia species.

A new genus and species of large-bodied caridean shrimp from the Crozet Islands, Southern Ocean (Crustacea, Decapoda, Lipkiidae) with a checklist of Antarctic and sub-Antarctic shrimps

A new, over 10 cm long, sub-Antarctic shrimp, Fresnerhynchus crozeti n. gen., n. sp. is described based on a unique specimen collected with long lines at 1889 m on the slope of a seamount northwest of the Crozet Islands. It is included in the previously monotypic family Lipkiidae Burukovsky, 2012 based on morphological and molecular data. However, the posterior pereiopods of Fresnerhynchus are reminiscent to those of the Rhynchocinetidae, especially by the short spinose dactyli, and by the absence of a sternal plate. The elusive nature of F. crozeti, which is a large and highly characteristic shrimp, is attributed to its putative habitat (hard bottom, steep deep sea slopes), which is difficult to sample with conventional gear, and the remote geographical location. A brief discussion on the biogeography of Antarctic and sub-Antarctic decapods is provided. A review of Antarctic and sub-Antarctic dendrobranchiate and caridean shrimps is appended.

Figure 29 In Two New Pseudorchomene Species From The Southern Ocean, With Phylogenetic Remarks On The Genus And Related Species (Crustacea: Amphipoda: Lysianassoidea: Lysianassidae: Tryphosinae)

FIGURE 29. Pseudorchomene rossi (Walker, 1903), male, 24 mm, ANT – XXIII / 8 sta. 698 – 1, Larsen B. A, left Md; B, tip of lacinia mobilis; C, right Gn 1; D, left coxa 4; E, right P 5; F, left Ep 1; G, left Ep 2; H, left Ep 3; I, left U 3.