The infraorder Anomura has long captivated the attention of evolutionary biologists due to its impressive morphological diversity and ecological adaptations. To date, 2500 extant species have been ...described but phylogenetic relationships at high taxonomic levels remain unresolved. Here, we reconstruct the evolutionary history-phylogeny, divergence times, character evolution and diversification-of this speciose clade. For this purpose, we sequenced two mitochondrial (16S and 12S) and three nuclear (H3, 18S and 28S) markers for 19 of the 20 extant families, using traditional Sanger and next-generation 454 sequencing methods. Molecular data were combined with 156 morphological characters in order to estimate the largest anomuran phylogeny to date. The anomuran fossil record allowed us to incorporate 31 fossils for divergence time analyses.
Our best phylogenetic hypothesis (morphological + molecular data) supports most anomuran superfamilies and families as monophyletic. However, three families and eleven genera are recovered as para- and polyphyletic. Divergence time analysis dates the origin of Anomura to the Late Permian ~259 (224-296) MYA with many of the present day families radiating during the Jurassic and Early Cretaceous. Ancestral state reconstruction suggests that carcinization occurred independently 3 times within the group. The invasion of freshwater and terrestrial environments both occurred between the Late Cretaceous and Tertiary. Diversification analyses found the speciation rate to be low across Anomura, and we identify 2 major changes in the tempo of diversification; the most significant at the base of a clade that includes the squat-lobster family Chirostylidae.
Our findings are compared against current classifications and previous hypotheses of anomuran relationships. Many families and genera appear to be poly- or paraphyletic suggesting a need for further taxonomic revisions at these levels. A divergence time analysis provides key insights into the origins of major lineages and events and the timing of morphological (body form) and ecological (habitat) transitions. Living anomuran biodiversity is the product of 2 major changes in the tempo of diversification; our initial insights suggest that the acquisition of a crab-like form did not act as a key innovation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Recent sampling on mesophotic deep banks in the northwestern Gulf of Mexico has produced a previously undescribed hermit crab assignable to the genus Cancellus H. Milne Edwards, 1836. Members of the ...genus are most often found to occupy cavities of eroded coral, siliceous sponges, porous calcareous rock fragments, algal concretions, or worm tubes as shelters. The present specimen was found loose as by-catch in a dredged rhodolith sample taken for algal life history studies. In situ, it likely occupied a cavity within one of the collected calcareous rhodoliths or small sponges in the by-catch. While our description is based on a single female specimen, the holotype is fully mature and intact, and it was solidly frozen in seawater until its coloration could be photographically documented and tissues extracted for sequencing. In comparison to the three other known western Atlantic species, the frontal rim of the carapace shield in the new species is continuous between the blunt lateral teeth as in C. ornatus Benedict, 1901 and C. viridis Mayo, 1873, and thus distinct from the subdivided front found in C. spongicola Benedict, 1901. The rim itself is somewhat flattened as in C. ornatus rather than inflated as in C. viridis. However, each of the ocular scales bears a pair of spines at the tip, as in C. viridis. The lower palms of the chelipeds, while distinctly rugose, do not have a separated patch of stridulating ridges comparable to those reported for C. spongicola. The yellow-orange to deep-orange pigmentation of the color pattern differs from fresh coloration in both C. ornatus and C. viridis, but that of C. spongicola is unknown for other than preserved specimens. Description of the single available specimen is in this case justified by the low likelihood for timely acquiring of additional samples from the type locality or adjacent habitats, most of which are deep banks warranting protection under pending habitat management changes. Our diagnosis includes GenBank accession numbers for COI sequences to facilitate future molecular phylogenetic comparisons.
The mole crab Emerita portoricensis Schmitt, 1935 was originally described solely on the basis of few key characters that were not precisely defined, giving reason to question subsequent reports of ...its distribution. The present study, prompted by recent collections documenting coloration in life, undertakes a comprehensive redescription of the species based on specimens of varied sizes from Puerto Rico, Belize, Costa Rica, and Panama. Collections from the northern Caribbean that at first take appear to represent a northernmost record of E. brasiliensis Schmitt, 1935 or southernmost occurrence of E. talpoida (Say, 1817), may be assignable E. portoricensis as now recognized. Among western Atlantic species, E. portoricensis and E. benedicti have to date been considered to have the dactylus of the first pereopod terminally subacute or sharply pointed, which purportedly separates them from E. brasiliensis and E. talpoida, western Atlantic species in which this article is terminally rounded. However, in E. portoricensis this character varies with specimen size and the magnification at which the distal extreme of the dactylus is examined, being rounded to varying degrees in all but the largest specimens. Even in sexually mature specimens of less than maximum size, this rounded tip is armed by a minute corneous spine in E. portoricensis, although it is less prominent than the terminal spine on the consistently more acute dactylus of E. benedicti at all adult sizes. Also, the carapace color in live specimens of E. portoricensis, as documented for specimens collected in both Belize and Panama, differs from that of E. brasiliensis, E. talpoida, and E. benedicti by typically including longitudinal and diagonal dark bars of olive brown on the branchial regions and a light longitudinal bar marking the posterior quarter of the median line. Posterior to the cervical groove, fine rugae of the carapace that form broken transverse lines are at most little diminished across the mid-dorsal longitudinal line in E. portoricensis and E. benedicti, somewhat more broken in E. brasiliensis, and distinctly diminished to all but absent at the midline in E. talpoida. Previously reported BINs in the Barcode of Life database include sequenced specimens from Costa Rica herein accepted as E. portoricensis. We exclude populations from Brazil that have been mis-assigned to E. portoricensis.
Marine crabs of the genus Persephona Leach, 1817 are restricted to American waters of the western Atlantic and eastern Pacific Oceans. Subfamilial assignment of this taxon has varied between authors ...and its species composition remain in question. We conducted a comparative study based on morphology and molecular phylogenetics for all ten recognized species of Persephona, along with Iliacantha hancocki. We tested whether Persephona finneganae, P. lichtensteinii, and P. crinita represent a single species as suggested by some authors; whether specimens identified as P. punctata, P. mediterranea, and P. aquilonaris warrant treatment as separate species; and whether I. hancocki should be regarded as a junior synonym of P. subovata. Diagnostic morphological characters (of the carapace, chelipeds, and third maxillipeds) were used along with gonopod (male first pleopod 1) features and live coloration. The 16S rRNA and the Cytochrome Oxidase I (COI) (DNA barcoding) mitochondrial genes were used as molecular markers. Both morphological and molecular analyses revealed that putative specimens of P. crinita from Brazil and those assigned to P. finneganae were no different from specimens presently assignable to P. lichtensteinii. P. finneganae is regarded as a junior synonym of P. lichtensteinii, and we apply P. crinita only to specimens we examined from the Gulf of Mexico. Specimens from Brazil previously reported as P. crinita are herewith concluded to represent P. lichtensteinii. Additionally, P. townsendi is a junior synonym of P. orbicularis, Iliacantha hancocki is concluded to be a junior synonym of P. subovata, while P. aquilonaris and P. mediterranea are found to represent separate species. On the basis of our revisions, eight species of Persephona are considered valid, and the reported distribution for P. crinita is restricted.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A new western Atlantic member of the ctenochelid genus Paragourretia Sakai, 2004 is described to accommodate a single unique specimen collected by dredge on muddy rubble substrates of the continental ...shelf in the southwestern Gulf of Mexico. Paragourretia sandrae n. sp. closely resembles Paragourretia biffari (Blanco Rambla & Liñero Arana, 1994), another regionally reported species for which photographs and additional illustrations are herein provided. While P. biffari and P. sandrae n. sp. are similar in habitus and known habitat to the more commonly encountered confamilial Dawsonius latispina (Dawson, 1967), the third maxillipeds in Paragourretia bear distinct exopods that are absent in Dawsonius Manning & Felder, 1991. As in eight other world congeners, P. sandrae n. sp. differs from both P. biffari and Dawsonius in lacking triangular ventrolateral projections on the sixth pleomere. It is further distinguished from P. biffari by lacking a distinctly incised notch in the anterodistal margin of the uropodal exopod and by absence of a median terminal spine on the telson. Additional sequence-quality specimens of P. sandrae n. sp. are required to clarify its relationships within the polyphyletic genus Paragourretia on a molecular genetic basis.
A new species of callianassid mud shrimp is described from outer continental shelf waters of the northwestern Gulf of Mexico, where it appears to commonly live in close association with sediments on ...or near natural hydrocarbon seeps. Recent genus-level taxonomic revisions of the Callianassidae, based on gene sequence analyses and comparative morphological studies, included specimens representing this new species, assigning it with strong support to the genus Pugnatrypaea Poore et al., 2019. The other known species of this genus are also typically found in offshore waters of continental shelves, but are all restricted in distribution to the Indo-West Pacific and are known from relatively few specimens. Collections of this new Gulf of Mexico representative of the genus are all from slightly deeper waters than for other known congeners, and commonly occur near hydrocarbon seeps, on some occasions being directly associated with sulfidic substrates that include waxy crude oil globules.
A new species of the pilumnid crab genus Pilumnus Leach, 1815, P. mantelattoi n. sp., is described and illustrated on the basis of a single ovigerous female specimen from Belize, bordering the ...northwestern Caribbean Sea. The holotype, an ovigerous female, was taken from an epifaunal accumulation of sponges, ascidians, and hydroids on red mangrove roots suspended in the water column. Superficially resembling Pilumnus floridanus Stimpson, 1871, with which it occurs sympatrically, it is distinguished from this and all other known western Atlantic species on the basis of both morphology and molecular markers.
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