Amphipholis squamata (Delle Chiaje, 1828)

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 : 590-596

publication ID	https://doi.org/ 10.1007/s13127-022-00600-9
persistent identifier	https://treatment.plazi.org/id/038A0373-7400-FF87-FCDD-FE57FB5BF8F2
treatment provided by	Felipe
scientific name	Amphipholis squamata (Delle Chiaje, 1828)
status

Treatment

Amphipholis squamata (Delle Chiaje, 1828) View in CoL

Material examined: 278 specimens. Barra de Mamanguape , Rio Tinto, PB: 6°45′49.35″S 34°55′4.85″W GoogleMaps , 2 spec., UFPB /ECH–2487 ; 2 spec., UFPB /ECH–2489 ; 5 spec., UFPB /ECH–2491 ; 27 spec., UFPB /ECH–2504; 6°45′54.0″S 34°55′04.0″W GoogleMaps , 4 spec., UFPB /ECH–2512 ; 3 spec., UFPB /ECH–2513 ; 2 spec., UFPB /ECH–2514; 6°45′54.0″S 34°55′04.0″W GoogleMaps , 4 spec., UFPB /ECH–2515. Bessa Beach, João Pessoa, PB: 7°04′36.5″S 34°49′24.1″W GoogleMaps , 11 spec., UFPB /ECH–2505 ; 23 spec., UFPB /ECH–2507 ; 14 spec., UFPB /ECH–2508 ; 4 spec., UFPB /ECH–2509; 7°04′33.0″S 34°49′30.0″W GoogleMaps , 2 spec., UFPB /ECH–2506 ; 4 spec., UFPB /ECH–2511; 7°04′35.0″S 34°49′23.0″W GoogleMaps , 31 spec., UFPB /ECH–2510. Cabo Branco Beach, João Pessoa, PB: 7°08′35.0″S 34°47′59.0″W GoogleMaps , 7 spec., UFPB /ECH–2516 ; 1 spec., UFPB /ECH–2520; 7°08′41.1″S 34°47′43.9″W GoogleMaps , 2 spec., UFPB /ECH–2517 ; 9 spec., UFPB /ECH–2518 ; 3 spec., UFPB /ECH–2519. Carapibus Beach, Conde, PB: 7°17′55.9″S 34°47′53.6″W GoogleMaps , 2 spec., UFPB /ECH–2521 ; 1 spec., UFPB /ECH–2524 ; 1 spec., UFPB /ECH–2525; 7°18′03.0″S 34°47′53.0″W GoogleMaps , 1 spec., UFPB /ECH–2522 ; 1 spec., UFPB /ECH–2523; 7°17′59.0″S 34°47′54.0″W GoogleMaps , 9 spec., UFPB /ECH–2526 ; 2 spec., UFPB /ECH–2527 ; 4 spec., UFPB /ECH–2528 ; 2 spec., UFPB /ECH–2529 ; 7 spec., UFPB /ECH–2530. Formosa Beach, Cabedelo, PB: 6°58′55.5″S 34°48′55.3″W GoogleMaps , 13 spec., UFPB /ECH–2531 ; 6 spec., UFPB /ECH–2532 ; 3 spec., UFPB /ECH–2534 ; 4 spec., UFPB /ECH–2537 ; 5 spec., UFPB /ECH–2538 ; 4 spec., UFPB /ECH–2539 ; 2 spec., UFPB /ECH–2540; 6°59′04.6″S 34°49′37.9″W GoogleMaps , 1 spec., UFPB /ECH–2533; 6°58′38.8″S 34°48′57.4″W GoogleMaps , 18 spec., UFPB /ECH–2535 ; 1 spec., UFPB /ECH–2536. Tambaba Beach, Conde, PB: 7°21′59.1″S 34°47′51.4″W GoogleMaps , 2 spec., UFPB /ECH–2541 ; 4 spec., UFPB /ECH–2542 ; 1 spec., UFPB /ECH–2543 ; 1 spec., UFPB /ECH–2545 ; 1 spec., UFPB /ECH–2546 ; 1 spec., UFPB /ECH–2548 ; 9 spec., UFPB /ECH–2549; 7°22′8.013″S 34°47′52.02″W GoogleMaps , 2 spec., UFPB /ECH–2544 ; 3 spec., UFPB /ECH–2547 ; 5 spec., UFPB /ECH–2550; 7°21′51.6″S 34°47′50.7″W GoogleMaps , 1 spec., UFPB /ECH–2551 .

tal; n vertebrae proximal. Abbreviations: ddmf, dorso-distal muscular fossae; dma, dorsal muscle area; ep, end processes; pk, protruding knobs; sp, septum; td, tooth sockets; vma, ventral muscle area; Vs, ventral groove; zd, zygocondyle; zp, zygosphene

Specimens selected for description Young early stage: individual UFPB /ECH–2518, Cabo Branco Beach, João Pessoa, PB; Young Intermediate Stage: individual UFPB / ECH–2518, Cabo Branco Beach, João Pessoa, PB; Adult: individual UFPB /ECH–2510, Bessa Beach, João Pessoa, PB.

Disc dorsal The young specimen in the early stage (DD = 0.76 mm) has circular disc, dorsally covered by some irregular scales (some circular), poorly overlapping, which have small translucent pores on their surface, since they are not yet fully calcified. The cpp is bordered by about three small and six larger scales ( Fig. 9a View Fig ).

The disc of the young intermediate stage (DD = 1.16 mm) is covered by smaller scales, more imbricated and numerous than in previous stage, with evident cpp, bordered by about eight large scales ( Fig. 9e View Fig ). On the other hand, the adult specimen (DD = 2.07 mm) has disc covered by medium, irregular, and imbricated scales, the largest arranged in the center of the disk ( Fig. 9i View Fig ).

The radial shields are small, occupying less than half the disc diameter, wider than long, fully united and with proximal edge rounded or straight ( Fig. 9b View Fig ), becoming larger and occupying almost half the diameter of the disc, slightly longer than wide, and fully united in intermediate specimen. In the adults, the radial shields are robust, longer than wide, with proximal edge slightly tapered and distal edge curved, anteriorly separated by one or two small triangular scales ( Fig. 9f, j View Fig ).

Ventral disc In the young early stage, the ventral interradial region presents larger and less imbricated scales than in the dorsal region, with bursal slit extending to second ventral arm plate ( Fig. 9c View Fig ). In the young intermediate stage, the ventral interradial region presents smaller and more imbricated scales than the previous stage ( Fig. 9g View Fig ). In the adult, these scales are smaller and more imbricated than the dorsal and wide bursal slits, extending to the fourth ventral arm plate ( Fig. 9k View Fig ).

In the young early stage, the structures of the jaw are poorly defined, which makes observation difficult, especially because calcification of these structures is still being completed. The oral shields are diamond-shaped, with rounded distal edge and tapered proximal, rectangular adoral shields, longer than wide and joined at the proximal edge. Each half jaw with LyOs possibly covered by the adoral shield, large, rectangular, wider than long AdShSp, globular and smaller 2nd AdShSp, a pair of robust and separated Ip ( Fig. 9d View Fig ).

In the young intermediate stage, the jaw region is similar to the previous stage ( Fig. 9h View Fig ), but the adult has lozengeshaped oral shields, smaller than intermediate stage; large and triangular adoral shields, joined in the proximal portion, with large, rectangular AdShSp, three to four times wider than long ( Fig. 9l View Fig ).

Arms In all stages, the number of five arms is maintained ( Fig. 9c, g, k View Fig ). Initially, the dorsal arm plates are quite small, as long as wide, almost rounded, with rounded distal edge and slightly curved proximal edge. The plates are fully separated from each other by the lateral arm plates ( Fig. 10a, c View Fig ). Triangular ventral arm plates, with straight distal edge ( Fig. 10b, d View Fig ); triangular 1st vap; tentacular scales absent ( Fig. 10b View Fig ). Large, rectangular lateral arm plates, longer than wide, with curved lateral edges; outer portion with three curved buttons “c”-shaped, parallel and separated, with arm spine joint of similar sizes, more robust dorsal sa ( Fig. 11a, b View Fig ) and inner portion of the lateral plate with three large perforations ( Fig. 11b View Fig ). Two to three robust, small, serrate arm spines, wider arm spine in the proximal region with three serrate distal segments ( Fig. 10e View Fig ).

In the young intermediary specimen, the dorsal arm plates are larger, as long as wide, with a tapered proximal edge and straight distal edge separated from each other by the lateral arm plates that are smaller than in the initial stage ( Fig. 10f, h View Fig ). Ventral arm plates are slightly longer than wide, with tapered proximal edge and straight distal edge, with indentations on the sides, providing the fitting of the tentacular scale ( Fig. 10g, i View Fig ). Tentacular scales absent on first arm segments; however, a small tentacular scale is present from the fourth segment and two are present from the eighth segment ( Fig. 10g View Fig ). Large lateral plates smaller than previous stage, wider than long, with curved lateral edges, ventral portion slightly elongate ( Fig. 11c, f, g View Fig ). Elongate, serrate arm spine, wider in the proximal region ( Fig. 10j View Fig ).

In adults, dorsal arm plates are triangular, wider than long, with an almost straight distal edge and a rounded proximal edge, separated by lateral plates ( Fig. 10l, n View Fig ). Ventral arm plates longer than wide, with straight distal edge and tapered proximal edge ( Fig. 10m, o View Fig ). Two small, triangular, tentacular scales arranged in parallel ( Fig. 10m View Fig ). Lateral arm plates without differentiation from the previous stage ( Fig. 11j, k, l View Fig ). In the proximal segments, the plates have four small, serrate arm spines, decreasing to three along the arm; arm spine robust, serrate, slightly tapered distally ( Fig. 10p View Fig ).

Color Initially, the specimens have a more translucent color ( Fig. 9a View Fig ), which throughout development becomes more whitish to grayish or light brown ( Fig. 9e, i View Fig ).

Microstructures The specimen in the young early stage has microstructures with stereom more porous. Oral plate wider than long, outer portion has an Abmaa long and long Rc that are well separated by a deep indentation ( Fig. 11d View Fig ); inner portion with Abaa, striations in muscle attachment, robust 1cot and 2cot ( Fig. 11e View Fig ).

adoral shields; AdShSp, adoral shield spine; 2nd AdShSp, second adoral shield spine; bs, bursal slits; cpp, central primary scale; Ip, infradental papillae; os, oral shields; rs, radial shields

l dorsal arm; m ventral arm; n dorsal arm plate; o ventral arm plate; p arm spine; q genital plate. Abbreviations: as, arm spine; cd, condyles; D, perforation; dap, dorsal arm plate; ts, tentacular scale; vap, ventral arm plate muscle attachment area; 1st cot, 1 compartment of the oral tentacle; 2nd cot, 2nd compartment of the oral tentacle; osp, oral spine plateau; pe, perforation; Rc, radial channel; sa, spine articular tubercle

In the young intermediate stage, the microstructures are less porous, with striations in the muscular insertion area of the oral plate well developed ( Fig. 11h, i View Fig ). The adult has little porous microstructures, with an external and internal oral plate similar to the previous stage ( Fig. 11m, n View Fig ).

Dental plates with three td, without sp, more robust and heart-shaped distal opening, other openings smaller and circular, with more robust distal buttons ( Fig. 12a). In the young intermediate specimen, the two distal openings of the dental plate are more robust and heart shaped, with robust buttons; the internal region has only two dental openings, with the proximal opening smaller ( Fig. 12f). The dental plate of the adult has a septate proximal opening; the inner region has three dental openings, with the proximal opening smaller ( Fig. 12k). Genital plate with robust condyle and deep groove in the inner region, not changing along the growth series ( Fig. 10k, q View Fig ).

In the young early stage, the vertebrae in dorsal view have condyles (cd) that are almost fused. In this very young specimen, the microstructures are more delicate, with small attachment sites for the distal aboral muscle (damf), inner aboral muscle (piamf), and outer proximal (pemf). The proximal oral muscle attachment site (pomf) is also in the process of development ( Fig. 12c). Vertebra in ventral view with narrow opening of distal oral internal muscle attachment site (doimf) ( Fig. 12b). Vertebra in distal view with proximal internal aboral muscle attachment site (piamf) slightly separated and point of pomf longer than wide ( Fig. 12d). Vertebra in proximal view with damf point is well separated, while the distal oral external muscle attachment site (doemf) is close ( Fig. 12e).

In the young intermediary specimen, the vertebra in dorsal view has a separated cd in the middle. Robust sites of damf, piamf, and peamf are well developed in pomf site ( Fig. 12h). Vertebra in ventral view with wide opening of the doimf site ( Fig. 12g). Vertebra in proximal view with the damf site joined distally, while the doemf site is very separated ( Fig. 12i). Vertebra in distal view with piamf site attached, and pomf site wider than long ( Fig. 12j).

The vertebrae in dorsal view of the adult vertebra with fused cd ( Fig. 12m), vertebrae in ventral view with wide opening in the doimf point ( Fig. 12l). Vertebrae in proximal and distal view are similar to the intermediate stage ( Fig. 12n, o). It is worth noting that the vertebrae closest to the mandible ( Fig. 13a–f View Fig ) are differentiated (smaller) from the distal vertebrae, wider than long, with smaller and more delicate muscle attachment sites.

The vertebrae closest to the jaw, in the intermediate stage in dorsal view, present cd and damf poorly developed, only the peamf, piamf, and pomf are very evident ( Fig. 13b View Fig ). In the adult, the piamf is more defined ( Fig. 13a View Fig ). Intermediate specimen with poorly defined muscle attachment sites in ventral view, and evident groove junction ( Fig. 13d View Fig ). In the adult, the junction becomes smoother ( Fig. 13c View Fig ), while the proximal and distal views of the vertebrae are poorly defined ( Fig. 13e, f View Fig ).

Seasonal influence on the growth rate The species Ophionereis reticulata ( Say, 1825) presented few specimens (Table 1 in the supplementary material); only 19 were collected, of which 13 in the dry season and six in the rainy season. For this reason, it was decided not to further consider their seasonal distribution. The general average of the DD was 7.73 mm with standard deviation (SD) of 2.58 mm. The smallest specimen collected in the dry period showed a DD of 2.84 mm and the biggest specimen had a DD of 11.70 mm. In the rainy season, the smallest specimen had a DD of 4.90 mm and the biggest, a DD of 10.48 mm.

The same occurred for Ophionereis squamulosa Koehler, 1914 (Table 2 in the supplementary material); only seven specimens were collected, five in the dry season and two in the rainy season. The general average of the DD was 8.91 mm, with a standard deviation (SD) of 1.28 mm. The smallest specimen collected in the dry period showed a DD of 8.53 mm and the biggest specimen had a DD of 11.12 mm. In the rainy season, the smallest specimen had a DD of 6.79 mm and the biggest, a DD of 9.07 mm.

In contrast, Amphipholis squamata (Delle Chiaje, 1828) presented the highest number of specimens collected, a total of 266 specimens, 135 during the dry season and 131 in the rainy season (Table 3 in the supplementary material). General average of the DD was 1.38 mm, with standard deviation (SD) of 0.43 mm. The smallest specimen collected in the dry period showed a DD of 0.58 mm and the biggest had a DD of 2.58 mm. In the rainy season, the smallest specimen had a DD of 0.55 mm and the biggest, a DD of 2.17 mm.

According to the DD, it was verified that the frequency of occurrence of Amphipholis squamata (Delle Chiaje, 1828) is lower for individuals below 1 mm, with most specimens in the juvenile stage measuring 1 to 1.75 mm, with the frequency remaining relatively constant until the adult stage. However, few reach a size above 2 mm ( Fig. 14 View Fig ).

Regarding the size of Amphipholis squamata (Delle Chiaje, 1828) specimens and their seasonal distribution, there was little influence between the analyzed periods and the variation of the DD. According to the results, younger specimens appear to be more frequent during the dry season and adults more frequent in the rainy season. Considering growth, the investigated stages showed linear increase in size, with a positive relationship between the DD and CB, rho = 0.69 and p <2.2 e- 16 ( Fig. 15).