Shinri Tomioka

Cosmopolitan or Cryptic Species? A Case Study of Capitella teleta (Annelida: Capitellidae)

Capitella teleta Blake et al., 2009 is an opportunistic capitellid originally described from Massachusetts (USA), but also reported from the Mediterranean, NW Atlantic, and North Pacific, including Japan. This putatively wide distribution had not been tested with DNA sequence data; intraspecific variation in morphological characters diagnostic for the species had not been assessed with specimens from non-type localities, and the species status of the Japanese population(s) was uncertain. We examined the morphology and mitochondrial COI (cytochrome c oxidase subunit I) gene sequences of Capitella specimens from two localities (Ainan and Gamo) in Japan. Specimens from Ainan and Gamo differed from C. teleta from Massachusetts in methyl-green staining pattern, shape of the genital spines, and shape of the capillary chaetae; we concluded that these characters vary intraspecifically. Species delimitation analyses of COI sequences suggested that worms from Ainan and Massachusetts represent C. teleta; these populations share a COI haplotype. The specimens from Gamo may represent a distinct species and comprise a sister group to C. teleta s. str.; we refer to the Gamo population as Capitella aff. teleta. The average Kimura 2-parameter (K2P) distance between C. teleta s. str. and C. aff. teleta was 3.7%. The COI data indicate that C. teleta actually occurs in both the NW Atlantic and NW Pacific. Given the short planktonic larval duration of C. teleta, this broad distribution may have resulted from anthropogenic dispersal.

Hexapleomera urashima sp. nov. (Crustacea: Tanaidacea), a tanaidid epibiotic on loggerhead sea turtles at Yakushima Island, Japan

We describe Hexapleomera urashima sp. nov. from the carapaces of loggerhead sea turtles (Caretta caretta) on Yakushi-ma Island, southwestern Japan, the primary nesting site for the North Pacific population of this turtle. Hexapleomera urashima closely resembles H. edgari Bamber collected from Australian loggerheads (South Pacific population), sharing a uropod with four articles and maxillipedal endites with distal spiniform setae, but differs in having the maxillipedal coxa with two simple setae, the maxillipedal endite with two tiny dorsosubdistal and two distal spiniform setae, the labial palp fused to the outer lobe of the labium, and the basal article of pleopod 3 without inner setae. Several characters (e.g., size or presence/absence of a dorsal triangular process on the male fixed finger; number of inner setae on the pleopodal endopod), assumed to be diagnostic for species in Hexapleomera, actually vary within H. urashima, indicating that reassessment of species diagnoses is warranted. Hexapleomera urashima showed two COI haplotypes differing by one substitution, but separated from representatives of four other genera by 32.2-48.4% K2P distance. Indices of saturation substitution indicated that COI is not useful for phylogeny reconstruction within Tanaididae.

Sabellaria jeramae, a new species (Annelida:Polychaeta: Sabellariidae) from the shallow waters of Malaysia, with a note on the ecological traits of reefs

A new species of the genus Sabellaria Lamarck, 1818 (Annelida: Polychaeta: Sabellariidae) is described from the intertidal zone of Jeram, Selangor, Malaysia. Sabellaria jeramae n. sp. is a gregarious species that constructs large reefs several hundreds of meters long and 50-200 m wide. The new species is distinguished from other congeners by the character combination of the presence of a single kind of middle paleae with conspicuous morphology, and outer paleae with long frayed teeth. Morphological features of the species are described and compared to those of all congeneric species. We also compare the reef structure and geographical distribution of the new species to those of the members of the family Sabellariidae around the world, demonstrating the ecological traits of the reefs.

Partial revision of Japanese Pectinariidae (Annelida: Polychaeta), including redescriptions of poorly known species

Eight species of Pectinariidae de Quatrefages, 1866 were recorded from Japan and adjacent waters. We studied four species of the family and redescribe the poorly known species from the Seto Inland Sea and Ariake Sound, Kyushu based on recently collected material. The species covered in this study are Amphictene japonica (Nilsson, 1928), Lagis bocki (Hessle, 1917), Pectinaria okudai (Imajima & Hartman, 1964) and Pectinaria hiuchiensis Kitamori, 1965.

Two new species of Mediomastus (Annelida, Capitellidae) from Tokyo Bay, Japan

Abstract Two undescribed species of polychaetes in Mediomastus (Annelida: Capitellidae) were collected from intertidal to shallow habitats in Tokyo Bay, Japan. These are M. duobalteus sp. n. and M. hanedaensis sp. n. Mediomastus duobalteus sp. n. is distinguishable from all congeners by the following characters: 1) segments 3, 4, 8–11 stainable with methyl green, 2) thoracic capillary chaetae unilimbate, 3) abdominal capillary chaetae absent, 4) paddle-like chaetae in the thorax absent, and 5) abdominal hooded hooks not flared. Mediomastus hanedaensis sp. n. is similar to M. warrenae Green, 2002, but differs from the latter in the shapes of the thoracic capillary chaetae and the abdominal hooded hooks, and the staining pattern with methyl green. In addition, a key to all Mediomastus species is provided.

Molecular Phylogeny of the Family Capitellidae (Annelida)

Capitellids have emerged as monophyletic in most but not all recent molecular phylogenies, indicating that more extensive taxon sampling is necessary. In addition, monophyly of most or all capitellid genera was questionable, as some diagnostic characters vary ontogenetically within individuals. We tested the monophyly of Capitellidae and eight capitellid genera using phylogenetic analyses of combined 18S, 28S, H3, and COI gene sequences from 36 putative capitellid species. In our trees, Capitellidae formed a monophyletic sister group to Echiura, and Capitella was also monophyletic, separated by a long branch from other capitellids. Well-supported clades each containing representatives of different genera, or containing a subset of species within a genus, indicated that Barantolla, Heteromastus, and Notomastus are likely not monophyletic. We mapped three morphological characters traditionally used to define capitellid genera (head width relative to width of first segment, number of thoracic segments, and number of segments with capillary chaetae) onto our tree. While Capitella showed unique character states, states in the other genera were decidedly not phylogenetically informative. Morphology-based capitellid taxonomy will require a fine-scale reevaluation of character states and detection of new characters.

Corrigenda: Two new species of Mediomastus (Annelida, Capitellidae) from Tokyo Bay, Japan. ZooKeys 422: 115-126.

[This corrects the article DOI: 10.3897/zookeys.422.7501.].