In this paper a description of Acritagasyllis longichaetosus, an enigmatic genus and species of Syllidae (Polychaeta), is given. The new genus is characterized by a lack of palps, eyes, and median antenna, having a single pair of tentacular (peristomial) cirri, distinct ventral cirri fused all along their length to parapodial lobes, a slender, coiled pharynx without trepan but with a pharyngeal tooth, compound chaetae with long shafts, distally enlarged and spinose, and long, filiform blades, quite similar to those belonging to members of the family Phyllodocidae. These characters are very unusual and unique among syllids. Some characters, like the presence of nuchal lappets, bayonet-shaped simple chaetae, and perhaps also the fusion of ventral cirri to parapodial lobes, bear some resemblance to those of species of Autolytinae. However, this new polychaete does not fit into this subfamily as it possesses ventral cirri, the chaetae are very different, and it lacks a trepan in the pharynx, nor can it be placed into any other subfamily, being an “incertae sedis” among the genera of Syllidae.

The first zoeal stage of the heterotreme domeciid crab Domecia glabra Alcock, 1899 (Trapezioidea), an obligate symbiont on hard corals, is described for the first time on the basis of laboratory-hatched material from Vanuatu. Its morphology is compared to other known zoeae of the Trapeziidae and Tetraliidae. The first stage zoea bears a remarkable similarity to larvae of the thoracotrematous Pinnotheridae, but the resemblance is superficial as their antennal morphologies are different. The key characters of Domecia ally it most closely with Tetralia in the Trapezioidea and supports molecular studies that they are sister taxa. Unfortunately, the zoeal and DNA studies do not give conclusive evidence with regard to whether the Domeciidae is truly trapezioid.

The ostracode genus Cypridinodes Brady, 1902 is reviewed, including reported ontogenetic changes, intraspecific variation and a generic diagnosis. Taxonomic notes on 20 described species are provided along with a discussion of systematic problems, particularly the inadequate description of some species, including the type of the genus. To facilitate identification of the 18 species, they are divided into four clusters.

Over the last 160 years, a possibly excessive number of species of the tanaidomorphan genus Leptochelia has been described based on its dimorphic males, followed by excessive synonymization to the point of suggesting one cosmopolitan species—called either L. dubia or L. savignyi—for taxa in which the male cheliped is shorter than the body length. It has become apparent over the last 25 years that, in a genus with little dispersive capability, there are numerous, and often sympatric, species of Leptochelia worldwide, none of them cosmopolitan, and distinguished principally on adult female morphology, although that morphology is very conservative. To resolve the resulting confusion over attribution of northeast Atlantic populations to one or other of the earlier-described species, specimens from Madeira, the type locality of L. savignyi, have been analyzed in comparison with material from the western English Channel and northwest Spain. The species is confirmed as Leptochelia savignyi sensu stricto, which is fully redescribed, compared with currently understood sympatric species, and intraspecific and ontogenetic variation is discussed.

Enterocola brementi Illg & Dudley, 1980 (Enterocolinae) is redescribed, based on females living in the type ascidian host Aplidium pallidum (Verrill) collected at Roscoff. These are compared with the female of E. mammiferus Chatton & Harant, 1922, found in A. asperum Drasche at Banyuls-sur-Mer. The comparison leads to the conclusion that the two are conspecific.

Recent fieldwork in the Shoal Creek drainage of the Tennessee River drainage in Tennessee has uncovered the presence of a new species of crayfish in the formerly monotypic genus Barbicambarus. The new species differs from the type species in possessing a median carina, less dense setae on the antennae, a less angular central projection, a spine at the dorsodistal margin of the merus of the cheliped, and a high level of divergence in the COI gene region. Collecting efforts have so far found the new taxon at only two locations and it is thought to be rare.

Cambarus (Puncticambarus) aldermanorum is a new species of crayfish that appears to be endemic to the lower Catawba and Saluda river basins in the Piedmont Plateau of South Carolina. Morphologically, it is most similar to C. (P.) hobbsorum and C. (P.) hystricosus. It differs from both species in having a long, narrow, lanceolate rostrum, and in lacking a proximomesial tubercle or spine on the ventral surface of the carpus. It further differs from C. (P.) hobbsorum in having hepatic spines, in other aspects of spination, and in having a broader areola. Cambarus (P.) spicatus of the Broad River basin is another very spinose crayfish that bears some resemblances to C. (P.) aldermanorum, from which it differs in having a broader rostrum with a very short acumen that is delineated at its base by marginal spines or tubercles, and a much broader, more punctate areola.

A new species of halfbeak, Hyporhamphus collettei is described from Bermuda. Previously it was considered conspecific with the western Atlantic H. unifasciatus (Ranzani, 1842). When compared to H. unifasciatus, H. collettei is a more slender species and has lower meristic counts. Meristics were significantly different for dorsal-fin rays (usually 14–15), pectoral-fin rays (usually 10), and total second-arch gill rakers (usually 21–23). A number of morphometric ratios aided in distinguishing this species from its closest geographic neighbors, H. meeki from the east coast of the United States and H. unifasciatus from the Caribbean, and Central and South American coasts. When preorbital length to orbital diameter is compared, it is usually less than 0.70 in H. collettei and greater than 0.70 in H. meeki. Ratio of body depths at pectoral- and pelvic-fin origins to standard length usually less than 0.12 in H. collettei, and greater than 0.12 in H. unifasciatus. Sequence data for 800 bp of mtDNA Cyt b gene clearly separate the Bermudan species from other species of Hyporhamphus by a minimum genetic distance of 0.034.