Metalia Gray, 1855
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publication ID |
https://doi.org/ 10.5281/zenodo.293989 |
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DOI |
https://doi.org/10.5281/zenodo.6231750 |
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persistent identifier |
https://treatment.plazi.org/id/191387FF-7174-FFCF-D1E6-FDB5FBE8F9B1 |
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treatment provided by |
Plazi |
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scientific name |
Metalia Gray, 1855 |
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Metalia Gray, 1855 View in CoL
Catalogue ot the recent Echinida, or sea eggs, in the collection ot the British Museum. Pt 1. Echinida Irregularia. Lon-
don, by order of the Trustees, p. 51.
Type species: Spatangus sternalis Lamarck, 1816 , by original designation.
Assigned species: Mortensen (1951a) lists seven Recent species ( M. dicrana Clark, 1917 ; M. latissma Clark, 1925 ; M. nobilis Verrill, 1867 ; M. robillardi (de Loriol, 1876); M. spatagus ( Linnaeus, 1758) ; M. sternalis ( Lamarck, 1816) ; M. townsendi Bell, 1904 ) in this genus, and raises doubts as to whether any fossil form can without question be attributed to this genus.
Distribution: Miocene of Egypt to Recent, Indo-Pacific.
Brissalius gen. nov. (gender: masculine)
Type species: Brissalius vannoordenburgi gen. nov., sp. nov. here designated (gender: masculine) Figs 1 View FIGURE 1 , 2 View FIGURE 2 and 9.
Diagnosis: Test outline broadly-ovate with indented anterior lateral ambulacra and sunken anterior ambulacrum forming a shallow frontal notch. Broadest point, halfway along the anterior petals, vertex mid-way along the posterior petals. Apical system ethmolytic, central, with four gonopores. Petals small, compact, the anterior pair slowly flex outwards, the posterior pair confluent for two thirds of their length proximally, the last third flexing outwards, with only the six distal pore-pairs of the inner series developed. The plastron is amphisternous, the labrum having a narrow posterior prolongation reaching the end of the first adjoining ambulacral plate. Peripetalous, anal and subanal fascioles are well developed. The subanal fasciole is shieldshaped resulting in a single sanitary funnel. Clavulae of the peripetalous and subanal fascioles have a ‘crown’ distally. Lobed funnel building tube feet are present in the anterior ambulacrum within the peripetalous fasciole and also within the subanal fasciole. Penicillate tube feet present only around the peristome. Plastron primary spines distinctly spatulate with sloping collars. Primary spines slender, curved, and ridged, widening and flattening dorso-ventrally distally. Miliary spines on both the oral and aboral surface only slightly curved, while those inside the peripetalous fasciole have a relatively broad shaft and a globular head with serrated ridges. Typical spatangoid rostrate, ophicephalous and triphyllous pedicellariae are present. Fanged openbladed globiferous pedicellariae occur in large numbers on the posterior of the oral ambulacra, fanged fistulate globiferous pedicellariae present in large numbers around the peristome with simple fistulate (with a round foramen and an arc of small teeth) occuring in small numbers on the oral ambulacra. Narrow-valved and spatulate tridentate pedicellariae present on the oral surface with a terminal-toothed form present adapically.
Holotype: NHM 2008.618 Natural History Museum, London.
Paratype: NHM 2008.619 Natural History Museum, London.
Etymology: This new genus has characters of both Brissopsis and Metalia which is reflected in the name by combining ‘Briss’ and ‘alius’ (masculine of the nominative ‘ alia ’, with ‘ alius ’ meaning other or changed). The species is named after Henk van Noordenburg who brought this new species to my attention.
Type locality: Off Siquijor Island in the Philippines (depth 200 m).
Description: The test is of medium size (at the widest points the holotype measures 38 mm (length) by 32 mm (width) by 19 mm (height at vertex), the plating thin and delicate. The outline is broadly-ovate ( Fig. 1 View FIGURE 1 A), with slightly indented anterior lateral ambulacra and sunken anterior ambulacrum forming a shallow frontal notch (anterior sulcus). The broadest point of the test is halfway along the anterior petals (20 % of the way along the length of the test) with the greatest height (vertex) halfway along the posterior petals. The posterior is truncated with an almost oblique vertical face, rounding adorally, protruding at the midpoint of the subanal fasciole ( Fig. 1 View FIGURE 1 C & D). The periproct is small and ellipitical ( Fig. 1 View FIGURE 1 F) being partially visible from above ( Fig. 1 View FIGURE 1 A), but not from below ( Fig. 1 View FIGURE 1 B). The anterior of the test rounds to a short, slightly blunt face. The oral surface is convex and steeply angled forming a distinct keel ( Fig. 1 View FIGURE 1 F); while the sides of the test are regularly arched aborally towards the sunken petal area ( Fig. 1 View FIGURE 1 E & F).
The anterior ambulacrum ( Fig. 1 View FIGURE 1 A) is narrow, non-petaloid and sunken. The pore-pairs are differentiated with lobed tube feet present aborally. Adapically the pore-pairs are uniserial with a perradial granular zone. The anterior and posterior paired ambulacra are petaloid ( Fig. 1 View FIGURE 1 A), narrow, of equal length and closed distally. The anterior pair slowly flex outwards for two-thirds of their length distally, the outer series at an angle of 25 degrees, increasing to 60 degrees for the last third of their length. The inner series are more greatly curved with only eight pore-pairs developed distally. The posterior pair being confluent for two thirds of their length proximally, the last third flexing outwards, with only the six distal pore-pairs of the inner series developed. The pores are elongated and non-conjugate, reducing in size towards the apical system. The outer pores in the inner series of the anterior petals are larger than inner pores, being almost equal in the outer series. The pores in both series of the posterior petals are approximately equal in size. A few irregular miliary tubercles are present along the proximal edge of the distal ambulacral plates of the posterior petals ( Fig. 1 View FIGURE 1 A). All other ambulacral plates within the pore-zones are smooth. Outside the pore-zones the anterior ambulacral plates have miliary tubercles within the plates and the occasional small primary tubercle adradially.
The aboral plates of interambulacra 1–4 are each raised centrally, forming a faint keel ( Fig. 1 View FIGURE 1 A). The posterior interambulacrum 5 is slightly concave sloping gently towards the posterior edge. Tuberculation on interambulacra 1–4 is predominantly uniform aborally with all tubercles perforate and weakly crenulate and set in horizontal series. In interambulacrum 5 a naked zone is present down the midline to the periproct with only miliary tubercles present. Larger primary tubercles are present within the peripetalous fasciole, particularly on the third and fourth plates of the posterior interambulacrum and around the surrounding plates of the front edge of the anterior petals. On the oral surface ( Fig. 1 View FIGURE 1 B) and around the periproct ( Fig. 1 View FIGURE 1 F), the primary tubercles are enlarged but less abundant. The sternum ( Fig. 1 View FIGURE 1 F & G) is densely tuberculated in radiating series, the tubercles decreasing in size towards a central ridge which terminates in a posterior protrusion ( Fig. 1 View FIGURE 1 C & D). The edges of the sternal system, the ambulacra and the area around the peristome are broadly naked ( Fig. 2 View FIGURE 2 B). The plastron ( Figs 1 View FIGURE 1 B & 2B) is amphisternous, the labrum having a narrow posterior prolongation reaching the end of the first adjoining ambulacral plate. The anterior edge is smooth forming a very slightly protruding lip. The peristome is situated anteriorly, has moderately developed surrounding phyllodes and is crescentshaped.
The apical system is situated centrally ( Fig. 1 View FIGURE 1 A), has four genital pores and is ethmolytic with genital plate 2 elongate separating both the posterior genital plates (G4 & G1) and posterior ocular plates (OcV & OcI). The anterior genital pores are smaller and closer together than the proximal pores, which are situated on a ridge that connects interambulacra 1 and 4.
The peripetalous fasciole crosses distally the non-petaloid ambulacrum but stays close to the petals on the other ambulacra. On the interambulacra the peripetalous fasciole curves only gently inwards, not following the direct line of the petals. The subanal fasciole is shield-shaped ( Figs 1 View FIGURE 1 F & G, 2F & G) with typically four pore-pairs in each side but no distinct radiating furrows. The band of clavulae is thinnest at the lower part, becoming broader towards the periproct. A relatively broad (compared to other Brissopsis ) band of clavulae forms an anal fasciole ( Figs 1 View FIGURE 1 A & 2A) connecting the subanal fasciole with the peripetalous fasciole.
The denuded test and spines are cream/white, while in life the dermis is typically beige/light-brown. Many of the specialised tube feet and pedicellariae have a black skin, visible as black flecks on the test.
Primary spines on the aboral surface are slender, curved (both laterally and dorso-ventrally), widening and flattening slightly dorso-ventrally distally ( Fig. 9 Ki & Kii). The spines have smooth longitudinal ridges which increase in width distally, terminating in slightly rounded tips. The neck of the spine is straight (not pinched) while the collar is prominent, sloping slightly upwards towards the dorsal surface of the spine. Primary spines within the peripetalous fasciole are shorter, with less curved shafts and broader, more flattened distal regions ( Fig. 9 Ji & Jii).
Primary spines on the oral surface ( Fig. 9 Ni & Nii) are similar to those aborally, but some have recurved shafts (curving in different directions proximally and distally) with more flattened and angular distal regions. Primary spines on the plastron (see Fig. 2 View FIGURE 2 B, D & F) are distinctly spatulate (spoon-shaped), with very sloping collars towards the dorsal surface.
Miliary spines on both the oral and aboral surface are only slightly curved dorso-ventrally ( Fig. 9 Li & Lii), the tips only very slightly widened and flattened. Those within the peripetalous fasciole have a relatively broad shaft that increases in width distally forming a globular head ( Fig. 9 Ii). The shaft typically has six to eight serrated ridges which increase in height distally.
Clavula structure is similar in the peripetalous and subanal fascioles with a long narrow shaft and a distinct ‘crown’ distally ( Fig. 9 O). The degree of development of the crown varies slightly with some clavulae having a more simplified structure ( Fig. 9 Iii).
Penicillate tube feet are present around the peristome (see Fig. 2 View FIGURE 2 B & G where they are visible as dark patches around the mouth). The suction discs of the anterior ambulacral aboral tube feet are formed of four to six lobes, while within the peripetalous and subanal fascioles ( Fig. 9 Pi & Pii) they are formed of six to ten lobes.
The sphaeridia are slightly elongate-round, occurring adorally not in grooves or pits. These have no ornamentation and thus offer no species-specific characters.
This species has a particularly diverse array of highly localised pedicellariae ( Fig. 9 A–H) all of which have three valves. Three distinct forms of globiferous pedicellaria are present. These can be grouped into two types, fistulate (tubular) and open-bladed, which only occur on the oral surface. Fanged open-bladed globiferous pedicellariae ( Fig. 9 Di–Diii) are forceps-like having straight, narrow, predominantly open valves (neck of blade is closed, gradually opening distally), with each valve terminating in two long, inward-facing fangs. The valves only meet where the fangs interlock, with one valve typically being shorter than the other two. The proximal region is small compared to the length of the valve; while the neck is short and attached to a very short simple, unornamented, stalk ( Fig. 9 Diii). The valves are covered in a black skin which is thick and glandular in appearance around the fangs. This is the likely source of venom as there are no internal glands or stalk glands present. This form occurs in large numbers on the posterior of the oral ambulacra ( Fig. 2 View FIGURE 2 G; visible as dark ‘dots’ on the posterior of the ambulacra).
Fanged fistulate globiferous pedicellariae ( Fig. 9 Ei–Eiv) have large curved valves that are closed and tubular with each valve having an inverted triangular opening distally ( Fig. 9 Ei), terminating in two long inward-facing fangs ( Fig. 9 Eii). The proximal regions of the valves are proportionally large, with large adductor muscle insertion points. The neck of the valve is muscular, with muscle strands entering through the outside of the proximal region through transverse slits into the adductor muscle insertion points. The stalk is very short with vertical projecting rods around its base ( Fig. 9 Eiv). A large glandular mound occurs on the distal region of each valve ( Fig. 9 Eiv), encasing all but the tips of the fangs and is the likely source of venom. This makes them easily visible on the test, where they occur in large numbers around the anterior of the oral ambulacra and around the peristome ( Fig. 2 View FIGURE 2 B).
Simple fistulate pedicellariae ( Fig. 9 Ci–Civ) occur in very small numbers on the anterior oral ambulacra. This form has highly curved tubular valves that terminate in a circular foramen with an arc (no tooth on the apex of the lower lip) of eight to ten small teeth. The proximal region of each valve is proportionally large, with large adductor muscle insertion points. The stalk is simple and very short, and is attached to the valves by a short muscular neck. The valves are covered in a thick black skin ( Fig. 9 Cii), which is evenly distributed.
Tridentate pedicellariae with straight valves occur as three forms: narrow-valved ( Fig. 9 Giii & Giv), spatulate ( Fig. 9 Gi & Gii) and terminal-toothed ( Fig. 9 Fi–Fiii). The narrow-valved form occurs only on the anterior of the oral ambulacra. This form has narrow open blades that taper distally, with small peripheral teeth along the edges of the blades, which interlock along their entire length. The ossicles of the blades consist of an open lattice distally, becoming tighter proximally with a Y-shaped apophysis at the neck of the blade ( Fig. 9 Giii). The proximal region is proportionally small, with small adductor muscle insertion points. The neck of the pedicellaria is short and muscular, attached to a short stalk (less than the length of the valves). The spatulate form ( Fig. 9 Gi) is similar to the narrow-valved form but with an expanded blade distally and is found posterior of the peristome on the oral ambulacra. This form typically has larger proximal regions than the narrowvalved form; however, intermediates between the two are present.
The third tridentate form has narrow valves with each valve terminating in a proportionally large distal tooth ( Fig. 9 Fi–Fiii). This form only occurs on the aboral surface within the peripetalous fasciole. Small peripheral teeth are present down half to three quarters of the length of the edges of the blades, which interlock distally. The proximal regions are proportionally large and triangular. The neck is thin ( Fig. 9 Fiii) and attached to a narrow short stalk (shorter than the length of the valves).
A single form of rostrate pedicellaria is present ( Fig. 9 Hi–Hiii), typical of the spatangoid type. This only occurs in very small numbers on the oral ambulacra. The valves are highly curved and narrow ( Fig. 9 Hii), the sides of the valves being non-denticulate with overturned lips giving a partially enclosed appearance ( Fig. 9 Hi). The distal region of the blade has a slightly overturned fan of small teeth ( Fig. 9 Hi). These overlap when the three valves are together, being the only point of contact for the blades. The neck is short and narrow, connected to a long stalk.
Triphyllous pedicellariae ( Fig. 9 Ai & Aii) occur orally and aborally with a short muscular neck on a midlength stalk (twice the length of the valves). The blades are rounded, tapering distally. Teeth are present along the edges of the valves, which interlock with those of the other blades along their entire length.
Ophicephalous pedicellariae with large proximal handles occur as a single form ( Fig. 9 Bi–Biv), present in large numbers on the oral ambulacra and in the subanal fasciole. The blades are highly constricted ( Fig. 9 Bi, Bii & Biv) resulting in an inverted triangular blade. The edges of the blades are denticulate with an overhanging lip distally. The teeth of the blades interlock both laterally and distally forming the jaw-set. This sits directly on the stalk, which measures four to five times the length of the valves.
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.