Due South: The evolutionary history of Sub-Antarctic and Antarctic Tritoniidae nudibranchs.

The Tritoniidae provides one of the most famous model species for neurophysiology and behaviour, yet a well-developed phylogenetic framework for this family is still incomplete. In this study, we explored the species-level taxonomy, phylogenetic relationships, and geographic distributions of the tritoniid nudibranchs. During numerous expeditions, specimens from southern South America, Sub-Antarctic Islands, and Antarctica were collected, documented alive, and fixed for anatomical descriptions and genetic sequencing. DNA from 167 specimens were extracted and sequenced for mitochondrial (COI, 16S) and nuclear (H3) markers. An additional 109 sequences of all available tritoniids plus additional outgroups were downloaded from GenBank for comparative purposes. Maximum Likelihood under the GHOST model of evolution and Bayesian inference using the GTR + GAMMA model produced congruent topologies from concatenated alignments. The results of ABGD, GMYC, bPTP, and mPTP species delimitation analyses suggest many separately evolving units that do not coincide with traditionally recognized species limits. Southern Ocean Tritoniella and Tritonia species split into several previously unrecognized species. This result is in accordance with the limited dispersal abilities of some southern tritoniids. Along with the most complete phylogeny of Tritoniidae to date, we also provided many taxonomic notes at the species and genus level. Tritoniidae species are yet another example of under-recognized diversity in the Southern Ocean.

Revisiting the diversity and distribution of the ophiuroids (Echinodermata: Ophiuroidea) from Peru.

While the Ophiuroidea of Peruvian waters have long been studied, there exists inconsistencies regarding taxonomy and spatial distribution records. Based on literature review and museum records, we provide an updated checklist of the ophiuroids accompanied by the first geographical distribution analysis. Peruvian waters host 36 species of Ophiuroidea (three doubtful), yet 15 previous records of species are considered invalid for the area. We recorded five new records of species for Peru: Amphiodia oerstedi, Diopederma daniana, Ophiocomella alexandri, Ophiolepis crassa, and Ophiophthalmus normani. Peruvian maritime area is divided into four areas: The Tropical Eastern Pacific area where 16 species of ophiuroids occur, the Transition Zone with 13 species, the Warm Temperate Southeastern Pacific with nine species, and the Deep Zone with 14 species. We found significant differences in species composition among areas (except among the Eastern Pacific and the Transitional Zone), and each of them is represented by particular species. According to the rarefaction curve, the inventory of ophiuroids for the country is not yet complete; therefore, we suggest performing more expeditions along the Peruvian waters focusing mainly on the deep zones which remain relatively unexplored to date.

Molecular and morphological systematics of Dolabrifera Gray, 1847 (Mollusca: Gastropoda: Heterobranchia: Aplysiomorpha).

Molecular and morphological data from newly collected specimens and a review of the literature and type material indicate that the widespread tropical sea hare Dolabrifera dolabrifera is a species complex of five genetically distinct taxa. The name Dolabrifera dolabrifera is retained for a widespread species in the Indo-Pacific tropics. Dolabrifera nicaraguana is endemic to the eastern Pacific. Dolabrifera ascifera, D. virens and a new species described herein are restricted to the tropical Atlantic, with partially overlapping ranges in the Caribbean region and St. Helena. The temperate Pacific species Dolabrifera brazieri is also distinct and endemic to temperate southeastern Australia and New Zealand. These species of Dolabrifera constitute highly divergent lineages and most contain unique internal anatomical characteristics, particularly in the male reproductive morphology and shell shape, making them relatively easy to identify upon dissection. However, externally all these species are extremely variable in colour pattern and morphology and are virtually indistinguishable. This is particularly problematic for identification in the Atlantic Ocean where three species co-occur in the Caribbean region.

New Hamacantha from Peru and resurrection of Zygherpe as subgenus (Demospongiae, Poecilosclerida, Hamacanthidae).

Two species of Hamacantha with tylostyles are reported here for the Peruvian coast, namely H. desmacelloides sp.nov. and H. hyaloderma. The former is the first species in the genus with apically microspined sigmas, similar to those known to occur in Neofibularia, and recently reported from genera Biemna, Desmacella, Rhabderemia and Sigmaxinella. Hamacantha hyaloderma was previously known from Mexico to Canada, and is here reported for the first time from the south east Pacific. The finding of a second species with tylostyles led us to reinstate subgenus Hamacantha (Zygherpe). The possible phylogenetic significance of apically microspined sigmas is discussed in view of recent findings on the basis of molecular data.

Ophioderma peruana, a new species of brittlestar (Echinodermata, Ophiuroidea, Ophiodermatidae) from the Peruvian coast.

Ophioderma peruana sp. n. is a new species of Ophiodermatidae, extending the distribution of the genus Ophioderma to Lobos de Afuera Island, Peru, easily distinguishable from its congeners by its peculiarly fragmented dorsal arm plates. Dense granules, rounded or polygonal cover the disc, the radial shields may be naked or completely covered by granules. A good character for recognizing this species in the field is the dorsal side of the disc which is brown with disc granules lighter cream and brown, the arms are mottled with whitish spots and the ventral part of the disc on the interradial part is brown and the radial part bright yellow.