Dendrochirotida Grube, 1840

Martins, Luciana & Tavares, Marcos, 2020, Positive association between PTN polymorphisms and schizophrenia in Northeast Chinese Han population., Zoological Studies 59 (2), pp. 141-149 : 2-6

Order Dendrochirotida Grube, 1840 Family PSOLIDAE Burmeister, 1837 Genus Psolidium Ludwig, 1886

Type species. Psolidium dorsipes Ludwig, 1886 [by monotypy]

Atlantic and Southern Ocean Species (Atlantic Sector): Psolidium prostratum Pawson & Valentine, 1981 ( NWA); P. complanatum Cherbonnier, 1969 ( NEA); Psolidium lonchostimum sp. nov. ( SWA); Psolidium nanoplax sp. nov. ( SWA); Psolidium disciformis ( Théel, 1886) (AsSO - Strait of Magellan); Psolidium dorsipes Ludwig, 1886 (AsSO - Argentine, Strait of Magellan); Psolidium gaini * Vaney, 1914 (AsSO); Psolidium incubans * Ekman, 1925 (AsSO); Psolidium pawsoni * O’Loughlin & Ahearn, 2008 (AsSO); Psolidium tenue * Mortensen, 1925 (AsSO); Psolidium whittakeri * O’Loughlin & Ahearn, 2008 (AsSO); Psolidium pulcherrimum Thandar, 2008 ( SEA); Psolidium pseudopulcherrimum Thandar, 2008 ( SEA). (*) Species also known from outside the AsSO.

Psolidium lonchostinum sp. nov. Martins and Tavares ( Figs. 1–3 ) urn:lsid:zoobank.org:act:C2B17FCD-41FE-4D98-BB75-8EA7348EFDC9

H o l o t y p e: 8.3 m m (M Z U S P 7 4 4), B r a z i l,

R E V I Z E E, o f f c o a s t o f R i o G r a n d e d o S u l,

33°41'S – 51°32'W, 02.iv. 1998, 200 m.

Paratypes: 7 specimens, 7–7.5 mm ( MZUSP 743), 8 specimens, 6–8.2 mm ( MZUSP 591), Brazil, REVIZEE, off coast of São Paulo, 24°20'S, 44°09'W, 258 m, 10. i.1998.

Etymology: The specific epithet is formed by the combination of two Greek words, lonche (spear) and ostinos (bony, Latinized to ostinum), and refers to the thorn-shaped ossicles (branched rods) found in the sole.

Diagnosis: Body flat, oval in outline, mouth and anus covered by a variable number of small and irregular scales, lacking oral and anal valves. Dorsal and lateral body with conspicuous imbricating scales covered by inconspicuous small tube feet (up to two per scale). Calcareous ring notched only in radial plates. Tube feet arranged in two rows, lacking midventral tube feet. Dorso-lateral ossicles are smooth multiperforated plates and branched rods (thorn ossicles). Sole ossicles are knobbed and perforated plate and smooth plates with slightly knobbed in edges. Dorso-lateral tube feet with perforated rods.

Description: Body flat, oval in outline, 6–8.3 mm long and 4–5.9 mm wide ( Fig. 1A ). Mouth and anus covered by a variable number of small and irregular scales (0.8–1 mm wide), up to two tube feet penetrate each scale dorsally and laterally ( Fig. 1B ), lacking oral and anal valves.

Marginal dorsolateral scales (0.1–0.3 mm) smaller than dorsal scales ( Fig. 1C ). Thin sole, lacking scales, tube feet arranged in a double series: inner series of large tube feet and outer peripheral series of smaller tube feet close to the ventral margin ( Fig. 1D ), lacking mid-ventral (sole) radial series of tube feet, except for a cluster (up to 5) posteriorly and anteriorly ( Fig. 1E ). Calcareous ring simple, lacking posterior processes; radial and interradial plates united only at the base, notched only at the radial plate ( Fig. 1F ).

Dorsal/lateral ossicles are smooth and perforated plates, irregular in outline, with undulating margins (100–120 μm long) and round holes (5–20 μm in diameter) ( Fig. 2B ) and branched rods (thorn ossicles) (40–60 μm long, Fig. 2C ). Dorsal tube feet with perforated rods (70–130 μm long), with undulating in margins ( Fig. 2D ).

Sole with single-layered and elongated plates (130–150 μm long), perforated at their entire length and knobbed at center and margins ( Fig. 2E–F ) and smooth plate ( Fig. 3A–E ), slightly knobbed in the margin (70–100 μm long). Ventral tube feet with perforated rods with irregular, curved and undulating margins (80–160 μm long) ( Fig. 3F ) and end-plate.

Distribution: Brazil: São Paulo (~ 24°S) and Rio Grande do Sul (~ 30°S), between 200 and 258 m.

Psolidium nanoplax sp. nov. Martins and Tavares ( Figs. 4–5 ) urn:lsid:zoobank.org:act:AC75BF38-07B5-4013-B197-DBDCDB1B6E3F

Holotype: 11 mm ( MZUSP 589 ), Campos Basin , southeastern Brazil, 21°41'S – 40°20'W, Campos Basin, Monitoring Program coll., xii.1991 to i.1992, 44 m.

Paratype: 1 specimen 8.5 mm ( MZUSP 592), same data as the holotype.

Etymology: The specific name is formed by the Greek words, nano (little) and plax (plate), in reference to the reduced length of the sole plates.

Diagnosis: Body elongate in large forms (8–10 mm long; 5.5–5.9 mm wide), small forms ventrally and dorsally flattened. Dorso-lateral body covered by multilayered imbricating scales without granules or tubercles. Lacking oral and anal valves. Calcareous ring notched only in the radial plates. Tube feet arranged in two rows, lacking mid-ventral tube feet. Dorso-lateral ossicles are knobbed multiperforated plates. Sole ossicles are knobbed perforated plates and “cup-like” perforated plates. Tube feet with perforated plates and end plate.

Description: Body elongate in large forms (10 mm long) ( Fig. 4A ); small forms ventrally and dorsally flattened (8 mm) ( Fig. 4B ).

Mouth and anus lacking valves ( Fig. 4B ); anal cone slightly raised ( Fig. 4C ). Dorsal and lateral body with conspicuous imbricating scales (0.8–1 mm) and without granules or tubercles at the surface. One inconspicuous tube foot present at each scale ( Fig. 4D ). Marginal dorsolateral ( Fig. 4E ) scales smaller than dorsal scales (0.1–0.3 mm). Ventral sole lacking scales, tube feet arranged in a double series: inner series of large tube feet and outer peripheral series of smaller tube feet close to ventral margin ( Fig. 4F ), midventral tube feet absent. Calcareous ring simple, lacking posterior processes, radial and interradial plates united only at the base; radial plate notched ( Fig. 4G–I ).

Dorso-lateral ossicles are knobbed and multiperforated single plates, flat, oval in outline, heavily knobbed on one side, smooth on the other surface, knobbed edges (150–170 μm long) and rounded holes 10–20 μm in diameter ( Fig. 5A ).

Sole with knobbed and multiperforated single plates, strongly concave, oval in outline, heavily knobbed on one side, smooth on the other surface, knobbed edges (70–100 μm long), and round holes 15–20 μm in diameter ( Fig. 5G ) and “cup-like” multiperforated plates, concave, oval in outline (50–70 μm long) 10–15 μm in diameter ( Fig. 5C–F ).

Dorsal tube feet with supporting rods ( Fig. 5B ), curved with one central perforation and one central apophysis (80–150 μm). Ventral tube feet with knobbed and multiperforated plates ( Fig. 5H–I ; (120–150 μm).

Distribution: Campos Basin, southeastern Brazil, between 20.5° and 23°S.

Figures

Fig. 1. (A–F) Psolidium lonchostinum sp. nov. (A–D) holotype (MZUSP 744). (A) upper view; (B) detail of dorsal tube feet (black arrow); (C) detail of lateral scales (white arrow); (D) ventral view; detail of ambulacral feet (note the inner and outer rows of tube feet: black and white circles, respectively); (E) paratype (MZUSP 591)) detail of ventral tube feet (black arrow); (F) outline of the calcareous ring [holotype] R, radial plate. IR, interradial plate. Note in F interradial plate entire and radial plate notched. Scale bars: A = 4 mm; D = 2 mm; E = 3 mm; F = 500 μm.

Fig. 2. (A–F) Psolidium lonchostinum sp. nov., holotype (MZUSP 744). SEM photomicrographs of the ossicles. (A) scale from dorsal body wall, showing canals for tube feet (white arrow); (B) smooth plate from dorsal body; (C) branched rods (thorn ossicle) (black arrow); (D) rod from dorsal tube feet; (E–F) knobbed plates from sole. Scale bars:A–B = 50 μm; C = 40 μm; D–F = 50 μm.

Fig. 3. (A–F) Psolidium lonchostinum sp. nov., holotype (MZUSP 744). SEM photomicrographs of the ossicles. (A) four-holed smooth plate from sole, ventral view; (B) four-holed smooth plate from sole, dorsal view; (C–D) multiperforated smooth plate from sole, dorsal view; (E) four-holed smooth plate from sole, lateral view; (F) rod from ventral tube feet, dorsal view. Scale bars: A–B = 30 μm; C = 40 μm; D–E = 50 μm; F = 80 μm.

Fig. 4. (A–F) Psolus nanoplax sp. nov. (MZUSP 589, 592). (A) lateral view of holotype preserved in ethanol (note anal cone in white arrow); (B) upper view of [paratype-MZUSP 592] preserved in ethanol (note mouth and anus in black and red arrows, respectively); (C) detail of anal cone [holotype-MZUSP 592] (note anal cone and papillae, in white and red arrows, respectively); (D) detail of dorsal tube feet [holotype-MZUSP 592] (red arrow); (E) detail of lateral scales [paratype-MZUSP 592]; (F) ventral view detail of ambulacral feet [paratype-MZUSP 592], (note the inner and outer rows of tube feet: black and white arrows, respectively); (G) calcareous ring (H) detail of retractor muscle (white arrow) and (I) outline of the calcareous ring [paratype-MZUSP 592]; R, radial plate. IR, interradial plate. Note, only radial plate notched. Scale bars: A = 5 mm; B = 4 mm; C = 500 μm, D = 500 μm, E = 0.5 mm; F = 2 mm; G–I = 500 μm.

Fig. 5. (A–I) Psolus nanoplax sp. nov. Martins & Tavares (MZUSP 589). SEM photomicrographs of the ossicles. (A) knobbed plate from dorsal body (B) supporting rod from dorsal tube feet; (C) “cup-like” plates from sole in dorsal view; (D) “cup-like” multiperforated plates from sole in ventral view; (E) “cup-like” four-holed plates from sole in dorsal view; (F) “cup-like” plates from sole in lateral view (G) knobbed plates from sole and (H–I) knobbed plates from ventral tube feet. Scale bars: A–B = 50 μm; C = 20 μm; D–I =, 30 μm.