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Friday, August 9th, 2019
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| 7:11a | [Mollusca • 2019] Worm-riding Clam: Montacutona sigalionidcola (Bivalvia: Heterodonta: Galeommatidae) from Japan and its Phylogenetic Position
Abstract A new galeommatid bivalve, Montacutona sigalionidcola sp. nov., is described from an intertidal flat in the southern end of the Kii Peninsula, Honshu Island, Japan. Unlike other members of the genus, this species is a commensal with the burrowing scale worm Pelogenia zeylanica (Willey) (Annelida: Sigalionidae) that lives in fine sand sediments. Specimens were always found attached to the dorsal surface of the anterior end of the host body. This species has a ligament lithodesma between diverging hinge teeth, which is characteristic of Montacutona Yamamoto & Habe. However, it is morphologically distinguished from the other members of this genus in having elongate-oval shells with small gape at the posteroventral margin and lacking an outer demibranch. Molecular phylogenetic analysis based on the four-gene combined dataset (18S + 28S + H3 + COI) indicated that this species is monophyletic with Montacutona, Nipponomontacuta Yamamoto & Habe and Koreamya Lützen, Hong & Yamashita, which are commensals with sea anemones or Lingula brachiopods. This result suggests that host shifting across different phyla occurred at least twice in this clade. Keywords: Mollusca, ectocommensal, Galeommatoidea, host shift, polychaete, scale worm, Sigalionidae, symbiosis
Systematics Superfamily Galeommatoidea J.E. Gray, 1840 Family Galeommatidae sensu Ponder, 1998 Genus Montacutona Yamamoto & Habe, 1959 Diagnosis. Shell typically suborbicular in shape with submedian umbones. Two pronounced and spread laterals in left and right valves. A calcified, white portion (i.e., lithodesma) situated in-between the spread laterals. Outer demibranch significantly reduced or absent. Montacutona sigalionidcola sp. nov. [Japanese name: Sunaurokomushi-yadori-gai] Diagnosis. Shell ovate-elongate in shape with a small gape at posteroventral margin. Only inner demibranch present. Distribution. Kushimoto (this study) and Tsubaki (Otani et al. 2005; this study), Kii Peninsula, Wakayama Prefecture, and Uchiura, Kamogawa, Boso Peninsula, Chiba Prefecture, Japan (Yanagi 2017).  Host. Pelogenia zeylanica (Annelida: Sigalionidae) (Fig. 3D–F). Host association. This species is tightly attached to the dorsal surface of the anterior end of the host by byssal threads (Fig. 3). The anterior end of the holotype was directed towards the anterior end of the host. The number of M. sigalionidcola per host ranged from one to four (Table 3). The infestation rate by M. sigalionidcola is high: roughly 80% of P. zeylanica harbored commensal bivalves (Tanaka, personal observations). Etymology: The species name is derived from the family name [Sigalionidae] of the host and the suffix -cola (Latin), meaning a dweller or inhabitant. Ryutaro Goto and Makoto Tanaka. 2019. Worm-riding Clam: Description of Montacutona sigalionidcola sp. nov. (Bivalvia: Heterodonta: Galeommatidae) from Japan and its Phylogenetic Position. Zootaxa. 4652(3); 473–486. DOI: 10.11646/zootaxa.4652.3.4 | ||||||||
| 9:12a | [Herpetology • 2019] Epictia rioignis • A Century of Waiting: Description of A New Epictia Gray, 1845 (Serpentes: Leptotyphlopidae) based on Specimens housed for more than 100 years in the collection of the Natural History Museum Vienna (NMW)
Abstract We describe a new species of Epictia based on eight specimens from Nicaragua collected and housed in the collection of the Natural History Museum Vienna for more than a century. The species differs from the congeners by the combination of external morphological characters: midtail scale rows 10; supralabials two, anterior one large and in broad contact with supraocular; infralabials four; subcaudals 14–19; middorsal scale rows 250–267; supraocular scales present; frontal scale distinct; striped dorsal color pattern with more or less triangular dark blotches on each scale; small white blotch in anterior part of dorsal surface of rostral present in five out of six specimens (two further specimens are lacking their heads); terminal spine and adjacent scales white. Eidonomic species separation from other Epictia spp. is also supported by a few qualitative and quantitative differences in vertebrae count and morphology. The new species is putatively assigned to the Epictia phenops species group based on external morphological characters and distribution.
  Epictia rioignis sp. nov. Diagnosis: Epictia rioignis sp. nov. can be distinguished from all congeners by the following combination of characters: (1) midbody scale rows 14; (2) midtail scale rows 10; (3) supralabials two, anterior one large and in broad contact with supraocular; (4) infralabials four; (5) subcaudals 14–19; (6) middorsal scale rows 250–267; (7) total number of precloacal vertebrae 231–248; (8) supraocular scales present; (9) frontal scale distinct, not fused with rostral; (10) striped dorsal color pattern with more or less triangular dark blotches on each scale; (11) upper half of eyes visible in dorsal view; (12) some caudals in posterior part of tail are fused in 50% of the specimens; (13) small white blotch in anterior part of dorsal surface of rostral present in about 83% of the specimens; (14) terminal spine and adjacent scales white.
Etymology: The specific epithet is an agglutination of the Latin nomen “ignis” which means fire and the proper noun “Rio” as an acronym for the Brazilian city of Rio de Janeiro. This name was chosen in honour to the Museu Nacional do Rio de Janeiro/UFRJ, Brazil’s oldest scientific institution with the largest South American collections of zoology, anthropology, geology and paleontology. Many of the precious collections pertaining to the zoology department (mostly invertebrates), anthropology, geology and paleontology were completely destroyed in the disastrous fire in its main building on September 2nd 2018. Due to historical neglection of this institution from the Brazilian government, added with substantial funding decrease in the past 5 years the museum did not receive sufficient money to fullfil basic safety standards—such as fire protection. The description of this new species, with specimens housed in a scientific collection for more than 100 years highlights one of the several importances of zoological collections in housing relevant material to understand the diversity of life, and also reinforce that such collections are timeless treasures for science. Such collections should receive strong attention in government investments as they contribute to the global development of science. Distribution and natural history: Epictia rioignis is currently known exclusively from its type series, from Corinto, Nicaragua. Conclusions: The biodiversity of scolecophidians worldwide is greatly underestimated and often unexpected (Wallach, 2016). Although most of the systematic changes in Epictia spp. have arisen from molecular studies (or at least provided a start point for additional taxonomical arrangements, see Wallach, 2016), morphological studies including both external morphology and internal anatomy are very important for systematic clarification of this group (present study). Even if molecular studies have aided on the identification of cryptic species, this study shows that the morphological analysis of collection specimens still reveals novel data for threadsnakes. This further emphasizes the importance of zoological collections in housing specimens that still allow description of new taxa based on specimens collected more than a century ago. Claudia Koch, Angele Martins and Silke Schweiger. 2019. A Century of Waiting: Description of A New Epictia Gray, 1845 (Serpentes: Leptotyphlopidae) based on Specimens housed for more than 100 years in the collection of the Natural History Museum Vienna (NMW). PeerJ. 7:e7411. DOI: 10.7717/peerj.7411   |
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