Ophionereis squamulosa Koehler, 1914

da Silva, Jailma Ferreira, Prata, Jéssica & Christoffersen, Martin Lindsey, 2023, Intraspecific variations in species of Ophiuroidea (Echinodermata) from the Tropical Southwest Atlantic, Northeast Brazil, Organisms Diversity & Evolution (New York, N. Y.) 23 (3), pp. 577-602 : 586-590

publication ID	https://doi.org/ 10.1007/s13127-022-00600-9
persistent identifier	https://treatment.plazi.org/id/038A0373-7404-FF9E-FF65-FF29FAC0FED0
treatment provided by	Felipe
scientific name	Ophionereis squamulosa Koehler, 1914
status

Treatment

Ophionereis squamulosa Koehler, 1914 View in CoL

Material examined: 9 specimens. Cabo Branco Beach, João Pessoa, PB: 7°08′41.1″S 34°47′43.9″W, 1 spec., UFPB / ECH–2439. Formosa Beach, Cabedelo, PB GoogleMaps : 6°58′55.5″S 34°48′55.3″W, 1 spec., UFPB /ECH–2440. Carapibus Beach, Conde, PB GoogleMaps : 7°18′03.0″S 34°47′53.0″W, 1 spec., UFPB /ECH– 2441 GoogleMaps ; 7°17′59.0″S 34°47′54.0″W, 1 spec., UFPB /ECH– 2442 GoogleMaps ; 7°17′55.9″S 34°47′53.6″W, 1 spec., UFPB /ECH– 2443. Bessa Beach, João Pessoa, PB GoogleMaps : 7°04′33.0″S 34°49′30.0″W, 2 spec., UFPB /ECH–2444. João Pessoa, PB GoogleMaps : 7°10′ S 34°42′ W, 2 spec., UFPB /ECH–643 GoogleMaps .

Specimens selected for description Young early stage: individual UFPB /ECH–643, João Pessoa, PB; Young Intermediate Stage: individual UFPB /ECH–2442, Carapibus Beach, Conde, PB; Adult: individual UFPB /ECH–2444, Bessa Beach, João Pessoa, PB.

Dorsal disc The specimen in young early stage (DD = 4.98 mm) had a pentagonal disc, covered dorsally by small and imbricated scales, the closest of the radial shields being bigger, with cpp not evident ( Fig. 5a View Fig ). The young in intermediate stage (DD = 6.87 mm) presents a pentagonal disc with reticulations ( Fig. 5e View Fig ). In the adult specimen, the disc is circular (DD = 11.12 mm), with bigger scales close to the radial shields and surrounding the disc ( Fig. 5i View Fig ).

The radial shields initially are arranged close to the arm, being small, triangular, longer than wide, and separate ( Fig. 5b View Fig ). Throughout growth, they become much more separate, small, twice as long as wide, and semicircular ( Fig. 5f–j View Fig ).

Ventral disc In the young early stage, the interradial region had smaller scales than in dorsal region, with slight reticulations, wide bursal slits that extend to the fifth ventral arm plate, with few evident genital scales ( Fig. 5c View Fig ). In the intermediate specimen, the bursal slits extend to sixth ventral arm plate, with some evident genital scales and papillae ( Fig. 5g View Fig ); the interradial ventral region from adult presents scales similar to dorsal region, with strong reticulations. Bursal slits extend to the seventh ventral arm plate, with many genital papillae in its edges and visible genital scales ( Fig. 5k View Fig ).

The young early specimen has robust oral shields, as long as wide, with proximal edge slightly tapered, scalene triangle-shaped adoral shields, with elongate proximal edge, which do not touch each other; robust madreporite, similar in shape to an arrowhead. Each half jaw with triangular LyOs, longer than wide, with elongated proximal edges that almost touch, large, flattened, spatulate AdShSp, larger than wide, narrower 2nd AdShSp, and two robust Ip ( Fig. 5d View Fig ).

Young intermediate specimen with more robust oral and adoral shields than in early stage, robust madreporite with pores in the distal region, triangular, laterally flattened, and narrow LyOs, much longer than wide, rounded 2nd AdShSp ( Fig. 5h View Fig ). In adult specimen, the oral shields are octagonal, with a small whitish circular depression in the middle portion and visible pores on the distal edge. Each half jaw with small, longer than wide LyOs, elongated proximal edge, dorsoventrally flattened, large, wider than long AdShSp, longer than wide 2nd AdShSp, and none, one or two Ip ( Fig. 5l View Fig ).

Arms In all stages, the number of five arms is maintained ( Fig. 5c, g, k View Fig ). Initially the dorsal arm plates are rounded, with proximal and distal edges straight, almost the same length and slightly tapered laterally ( Fig. 6a, c View Fig ); small, semicircular accessory plates ( Fig. 6a, e View Fig ); ventral arm plates rectangular to triangular, longer than wide, with a straight distal edge, that has a strong indentation, tapering, the lateral portion of the plate with slight indentations, which provides fitting for the tentacular scale ( Fig. 6b, d View Fig ); small and square 1st vap ( Fig. 5d View Fig ); a large, spatulate tentacular scale ( Fig. 6b View Fig ); lateral arm plates with curved proximal region, the outer portion with three buttons “c”-shaped, well curved, parallel and separate, the middle spines of the greater arm joining ( Fig. 7a, c View Fig ); dorsal sa more robust, internal portion of the plate with a single large perforation ( Fig. 7b View Fig ). Arm pines wider in proximal region ( Fig. 6r View Fig ).

The young intermediate specimen has trapezoidal dorsal arm plates, with straight distal edge and curved proximal edge ( Fig. 6g, i View Fig ); small accessory plates, with straight proximal edge and curved distally ( Fig. 6g, k View Fig ); rectangular ventral arm plates with straight distal edge, which has a strong indentation, as well as the lateral portion ( Fig. 6h, j View Fig ); small and triangular 1st vap ( Fig. 5h View Fig ); lateral arm plates with proximal region longer ( Fig. 7f, g View Fig ), internal portion of the lateral plate with a single large perforation ( Fig. 7f View Fig ). Arm spine longer in the distal region, rod shaped ( Fig. 6l View Fig ).

Adult specimen has dorsal arm plates wider than long, with slightly rounded distal edge that keeps its length shorter than the proximal in virtually all arm segments ( Fig. 6m, o View Fig ); robust accessory plates, occupying the entire lateral side of the dorsal plates ( Fig. 6m, q View Fig ); square ventral arm plates ( Fig. 6n, p View Fig ); 1st vap with slightly tapered proximal edge and rounded distal edge ( Fig. 5l View Fig ); a large, spatulate tentacular scale, exceeding more than half the length of the ventral arm plate ( Fig. 6n View Fig ); lateral arm plates with proximal region “c”- shaped, more elongated and less curved than that in intermediate stage. Ventral portion is more robust and elongated ( Fig. 7j, l View Fig ), the inner region of the plate has a single large perforation positioned in the ventral region ( Fig. 7k View Fig ). Arm spine longer and with a slightly flattened apex, the median being bigger ( Fig. 6r View Fig ).

Color In the early young specimen, the color is whitish, dorsal disc with fine reticulations, which are more evident in the shields; AdShSp, adoral shield spine; 2nd AdShSp, second adoral shield spine; bs, bursal slits; Ip, infradental papillae; LyOs, Lyman ossicle; os, oral shields; rs, radial shields; 1st vap, first ventral arm plate spine. Adult specimen: m dorsal arm; n ventral arm; o dorsal arm plate; p ventral arm plate; q accessory plate; r arm spine. Abbreviations: ap, accessory plate; as, arm spine; dap, dorsal arm plate; ts, tentacular scale; vap, ventral arm plate muscle attachment area; 1st cot, 1 compartment of the oral tentacle; 2nd cot, 2 compartment of the oral tentacle; osp, oral spine plateau; pe, perforation; Rc, radial channel; sa, spine articular tubercle center of the disc ( Fig. 5a View Fig ), whitish arm plates without dark transverse bands ( Fig. 6a View Fig ). The intermediate specimen presents dorsal and ventral disc with fine reticulations, thicker and more diffuse than in previous stage ( Fig. 5e View Fig ), arm plates with transverse bands that are intercalated between four and three lighter and one darker arm plate ( Fig. 6g View Fig ). In adult, the color is light brown with disc covered by fine dark brown reticulation, which form non-uniform circles ( Fig. 5i View Fig ), arms with transverse bands that alternate between four to six lighter plates and one darker plate ( Fig. 6m View Fig ).

Microstructures The specimen in young early stage of growth has microstructures with stereom more porous ( Figs. 6 View Fig , 7 View Fig , and 8). Oral plate wider than long, outer part with long abmaa and short Rc ( Fig. 7d View Fig ); inner part with poorly defined abaa, without stretch marks in the muscle attachment area, 1cot robust ( Fig. 7e View Fig ). The microstructures of the young intermediate specimen are slightly less porous than the early stage, with oral plate as long as wide, outer portion with a side of abmaa more defined and bigger, also Rc longer ( Fig. 7h View Fig ); inner portion with abaa defined, wider dorsally, striations of muscular insertion present, arrangement parallel or perpendicular, 1cot and 2cot robust and well delimited ( Fig. 7i View Fig ).

The adult specimen has little porous and more delimited microstructures than the intermediate stage. Longer oral plate, outer part with an abmaa side well delimited and bigger, with Rc bigger than previous stage ( Fig. 7m View Fig ) and inner part with abaa without the striations of the muscular insertion ( Fig. 7n View Fig ).

Dental plate of the early stage is very delicate and fragile. In intermediate specimen, the dental plate is elongated, slightly wider in the proximal region, outer portion with two td, the most proximal much bigger than distal, with thick pk; internally, it has two dental cavities divided into four td separated by sp narrower in proximal portion and thicker in distal ( Fig. 8a View Fig ). The adult specimen presents an elongated dental plate, with outer portion with two td, the most proximal bigger than distal and with more pk than previous stage. Internally, it has two dental cavities divided into four circular and small td, separated by more robust sp ( Fig. 8j View Fig ).

Zygospondylic type vertebrae. In the initial stage, the dorsal and ventral vertebrae are as long as they are wide ( Fig. 8b, c View Fig ), the medial portion of the dorsal vertebra is “T”- shaped, with elongate ep and ddmf groove deep and narrow, ventral view of the vertebrae shows elongated and deep vg, laterally expanded in medial portion; vg joint very evident, especially in the zp portions that are fused with pair of zd, projecting beyond the zd ventral edge, distal and proximal view of the vertebrae wider than long ( Fig. 8d, e View Fig ), with Dma bigger than Vma.

Intermediary form with Dma and Vma bigger in distal and proximal view than in early stage ( Fig. 8h, i View Fig ). The other vertebrae do not show variations in comparison with the previous stage ( Fig. 8f, g View Fig ). In the adult, the dorsal view of the vertebrae have longer ep than in the intermediate stage ( Fig. 8k View Fig ). The remaining vertebrae do not present variations compared to the previous stage ( Fig. 8l, m, n View Fig ).