Weltnerium, ZEVINA, 1978

Gale, Andrew Scott, 2016, Phylogeny of the deep-sea cirripede family Scalpellidae (Crustacea, Thoracica) based on shell capitular plate morphology, Zoological Journal of the Linnean Society 176 (2), pp. 266-304 : 301-302

GENUS WELTNERIUM ZEVINA, 1978 B

FIGURES 1F, G , 3D, H , 7A–J , 8D, H, L , 12A–H

Type species

Scalpellum nymphocola Hoek, 1883 , original designation of Zevina 1978b.

Diagnosis

Inframedian latus pentagonal, with subparallel lateral margins, somewhat taller than broad; umbo central, usually close to rostrolatus margin. Rostrum well developed, large trapezoidal to rectangular external surface, extending over full height of rostrolatera. Scutum markedly trapezoidal, scutal and tergal margins short, basal–occludent angle acute (60°), tergal– upper latus angle 120°. Pit for dwarf males deep, oval, transverse.

Synonyms

Ornatoscalpellum Zevina, 1978a , Tarasovium Zevina, 1978a (partim), and Anguloscalpellum Zevina, 1978b (partim).

Referred species

Scalpellum stroemii M. Sars, 1859 , Scalpellum gibberum Aurivillius,1892 , Scalpellum ornatum Gray, 1848 , Scalpellum nymphocola Hoek, 1883 , Scalpellum convexum Nilsson-Cantell, 1921 , Scalpellum cornutum G.O. Sars, 1879 , Scalpellum natalense Barnard, 1924 , Scalpellum valvulifer Annandale, 1910 , Scalpellum recurvirostrum Hoek, 1883 , and Scalpellum angulare Nilsson-Cantell, 1930 .

Remarks

Weltnerium , as diagnosed here, is a monophyletic derived group characterized by a pentagonal inferior median latus with a low umbo, a tall, narrow rostrum with a large external surface, a markedly trapezoidal scutum, and a large transverse receptacle for dwarf males. Forms with subapical carinal umbones (‘ Ornatoscalpellum ’) and projecting carinolatera (some ‘ Tarasovium ’) fall into this category. It is not known from the fossil record.

Figures

Figure 1. Morphology and nomenclature of the scalpellid capitulum, and constituent carina, tergum, and scutum. A–C, I, Amigdoscalpellum truncatum (Hoek, 1883): A, dorsal (carinal) view; B, lateral view; and C, ventral (rostral) view. D, E, carina of Catherinum striolatum (G.O. Sars, 1877) in dorsal and lateral aspect. F, G, scutum of Weltnerium stroemii (M. Sars, 1859) in internal and external views, respectively. H, Amigdoscalpellum rigidum (Aurivillius, 1898), tergum in external aspect. For abbreviations, see Table 2. For details of localities etc., see Table 1. Scale bars: A–C, 5 mm; D–I, 1 mm.

Figure 3. Lateral aspects of Amigdoscalpellinae: A, Catherinum striolatum (G.O. Sars, 1877); B, Catherinum recurvitergum (Gruvel, 1900); C, Catherinum novaezelandiae (Hoek, 1883). D, Weltnerium nymphocola (Hoek, 1883); E, Amigdaloscalpellum rigidum (Aurivillius, 1898); F, Amigdaloscalpellum truncatum (Hoek, 1883); G, Amigdaloscalpellum sculptum (Hoek, 1907) H, Weltnerium stroemii (M. Sars, 1859). See Table 1 for localities. Scale bars: 5 mm.

Figure 7. Evolution of lateral plate morphology, dorsal side: A–E, Weltnerium stroemii (M. Sars, 1859); F–J, Weltnerium nymphocola (Hoek, 1883); K–O, Catherinum novazelandiae (Hoek, 1883); P–T, Catherinum striolatum (G.O. Sars, 1877); U–Y, Amigdoscalpellum rigidum (Aurivillius, 1898). External aspect of carinolatus (A, F, K, P, U); interior of carinolatus (B, G, L, Q, V); external view of inframedian latus (C, H, M, R, W); dorsal (carinal) view of basal capitulum (D, I, N, S, X); enlarged lateral view of basal capitulum (E, J, O, T, Y). Note the changes in the nature of the articulation between the carinolatera of a pair (interpenetrant, X; opposed double articulation, D, I, N, S) and those in the shape of the inframedian latus (triangular, W; waisted hourglass, M, R; pentagonal, C, H). See Table 1 for details of localities. Scale bars: A–C, F–H, M, P-R, U–V, 0.5 mm; D, E, I, J, N, O, S, T, X, Y, 1 mm.

Figure 8. Scalpellid scuta and terga. Scuta: A, E, Arcoscalpellum sociabile (Annandale, 1905); B, F, Amigdoscalpellum rigidum (Aurivillius, 1898); C, G, Catherinum hispidum (G.O. Sars, 1890); D, H, Weltnerium stroemii M. Sars, 1859). Terga: I, Arcoscalpellum michelottianum (Seguenza, 1876); J, Amigdoscalpellum rigidum; K, Catherinum hispidum; L, Weltnerium stroemii. See Table 1 for details of localities. Note the overall progression of morphological change from left to right in the shape of the scutum, with the basal–occludent angle becoming more acute, and the basal–upper latus angle more obtuse, leading to a more trapezoidal outline. Additionally, a small tergal surface develops, and the umbo becomes incurved, and the dwarf male receptacles become larger and better defined. The terga change from an oval– rhombic outline (I) to a right triangular one (J–L), the ventral margin has developed a narrow supracarinal surface (scs), with an inflexion where the tip of the carina rests against the carinal margin. See Table 1 for details of localities. Scale bars: K, 2 mm; A, E, F, J, M, N, 1 mm; B–I, L, 0.5 mm.

Figure 12. Evolution of rostra and rostrolatera plate morphology, ventral side: A–D, Weltnerium stroemii (G.O. Sars, 1859); E–H, Weltnerium nymphocola (Hoek, 1883); I–L, Catherinum novazelandiae (Hoek, 1883); M–P, Catherinum striolatum (G.O. Sars, 1877); Q–T, Amigdoscalpellum rigidum (Aurivillius, 1898), rostrum in ventral rostral aspect (A, E, I, M, Q); rostrolatus in external (B, F, J, N, R) and internal (C, G, K, O, S) views. Basal capitulum in ventral (rostral) aspect (D, H, L, P, T). The rostrum is tiny, with only a small external face (I, M, Q) in more basal taxa. In the most derived taxa, the central ridge has an external surface over the height of the plate (A, B). Scale bars: A–D, F–H, J–L, N–P, R–T, 0.5 mm; E, I, M, Q, 0.2 mm.