Barbadoschiton, Sirenko & Anseeuw, 2024
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publication ID |
https://doi.org/10.35885/ruthenica.2024.34(4).4 |
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publication LSID |
lsid:zoobank.org:pub:8D7E9371-6905-4325-9F63-EA9C25E0025E |
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persistent identifier |
https://treatment.plazi.org/id/815887A4-FFE2-7A4C-0095-0F2FFAB4C79F |
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treatment provided by |
Felipe |
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scientific name |
Barbadoschiton |
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Barbadoschiton View in CoL bromleyi ( Ferreira, 1985)
( Figs 1–5 View FIG View FIG View FIG View FIG View FIG )
Ischnochiton bromleyi Ferreira, 1985: 195 View in CoL , figs 4–8. Connexochiton bromleyi Kaas, Van Belle, 1987: 259 View in CoL , fig. 117,
map 32; Sirenko, 2021: 98.
Type material. Holotype in California Academy of Sciences, Department of Invertebrate Zoology, San Francisco ( CASIZ 043883 ) and paratype (CA- SIZ 043884, now disarticulated).
Type locality. Barbados, Six Men’s Bay , 13 ⁰15’N , 59 ⁰39’W, 30 m.
Updated description. Animal of small size, body length of the studied specimen 2.5 mm, elongate, rather elevated (dorsal elevation 0.52 in valve V) ( Fig. 2G View FIG ), valves thin, little beaked, carinated, color of tegmentum cream mottled with brown.
Head valve semicircular, posterior margin widely V-shaped, notched in the middle ( Fig. 2A View FIG ). Intermediate valves rather narrow, anterior margin convex in valve II and straight in other valves ( Fig. 2B, C View FIG ), side margins obliquely rounded, hind margin slightly concave at both sides of the prominent apex, lateral areas strongly raised. Tail valve semicircular ( Fig. 2D, H View FIG ), about twice as wide as long, front marginal most straight, mucro anterior, pointed, postmucronal area decidedly depressed, concave.
Tegmentum of head valve, lateral areas of intermediate valves and postmucronal area of tail valve covered with small granules (48 x 48 µm) arranged in quincunx, each granule with one pore of megalaesthete and four pores of micraesthetes ( Fig. 3A View FIG , 5A View FIG ). Tegmentum of central areas of intermediate valves and antemucronal area of tail valve covered with drop-shaped granules (33 x 25 µm) arranged in quincunx ( Fig. 2F View FIG , 5B View FIG ). In pleural areas granules form rows which posteriorly converging to jugal areas resulting in a net quincunx-pattern ( Fig. 2C View FIG ). Each granule with oval pore of megalaesthete (8 x 6 µm) ( Fig.2F View FIG , 5B View FIG ).
Articulamentum weakly developed, translucent, apophyses semioval, continuous across shallow sinus through a well developed jugal plate, slit formula 7/1/4, teeth of insertion plates thickened and smooth ( Fig. 2E View FIG ).
Girdle of moderate width, only three times nar- rower than valve V, dorsally covered with strongly bent, close set, regularly imbricating scales (30–44 × 62–88 μm) (Fig. B-D, 5E), with 11–14 distinct flat riblets on the exposed part of the scale, interstices as wide as the riblets. Marginal spicules consisting of five kinds: (1) rare long, smooth needles (160–190 × 13–15 μm) ( Fig. 3C View FIG , 5D View FIG ) on short bristle; (2) flattened, obtusely pointed spicules (21–27 × 16 μm) (3B, 5G) with three ribs on one side; (3) spicules (55 x 20 µm) ( Fig. 3B View FIG , 5F View FIG ) on one side curved from sides and with 7 longitudinal ribs, on the other side with longitudinal groove; (4) numerous, small spicules (32 x 10 µm) ( Fig. 3B,C View FIG , 5C View FIG ) with 5 longitudinal ribs and one longitudinal groove; (5) flat, obtuse spicules (40 × 22 μm) ( Fig. 3B View FIG , 5H View FIG ) with two warts on upper half.Ventral spicules of two kinds: (1) main flattened, rectangular spicules (48 x 18 µm) ( Fig. 3B View FIG , 4A, B View FIG , 5I View FIG ) with appendix on top and three weak longitudinal ribs on external part, and (2) small distally pointed spicules ( Fig 3B View FIG , 4A,B View FIG , 5J View FIG ), smooth on the outer side and with two longitudinal grooves on the opposite side of the spicules (35–50 x 11–12 µm). The latter are attached in transverse rows with their proximal part between the main ventral spicules.
Radula of the paratype with 35 rows of mature teeth, major lateral teeth of radula with tridentate head, middle denticle longer than others [ Kaas, Van Belle, 1987].
Distribution. Known from the type locality (off
Barbados), Flower Garden Banks in the Gulf of Mexico , and Martinique Island, 30–84 m.
Remarks. Barbadoschiton bromleyi , a distinctive species within the Ischnochitonidae family, dem- onstrates unique attributes not observed in other chitons.These unique attributes encompass the complex sculpture of its tegmentum and the atypical armament of its girdle. Barbadoschiton bromleyi is character- ized by the presence of drop-shaped granules with a singular pore of megalaesthete, specifically located on the central areas of its valves. This feature sets it apart from other chitons in the Chitoninae suborder. Moreover, flattened granules with five aesthetes pores are found on the head valve, lateral areas of intermediate valves, and the postmucronal area of the tail valve, further distinguishing Barbadoschiton bromleyi .
It’s worth noting that this species exhibits four types of marginal ribbed spiculae, a feature absent in other chitons.Additionally, this species possesses ventral distally pointed spicules with two longitudinal grooves, arranged in transverse rows above the primary flattened ventral spicules, which also exhibit longitudinal ribs. These unique spicules contribute to the classification of Barbadoschiton bromleyi into a separate genus within the Ischnochitonidae family. The function of these spicules remains unknown.
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Royal British Columbia Museum - Herbarium |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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Barbadoschiton
| Sirenko, Boris & Anseeuw, Bruno 2024 |
Ischnochiton bromleyi
| Kaas P. & Van Belle R. A. 1987: 259 |
| Ferreira A. J. 1985: 195 |