Chthamalus grazianii, Carriol, René-Pierre, 2008

Carriol, René-Pierre, 2008, New genus and new species of Cirripedia (Chthamalidae, Tetraclitidae, Archaeobalanidae and Balanidae) from the Middle Miocene of the faluns of Touraine (France), Zootaxa 1675, pp. 31-48 : 34

Chthamalus grazianii sp. nov.

Figs. 1 (1a–11) and 3 (9–10)

Diagnosis: Wall plates thin, external surface smooth; scutum much longer than broad with apical angle less than 90°, adductor muscle pit longer than wide close to occludent margin, and without lateral depressor muscle pit; tergum club-shaped.

Etymology: The species is named for F. Graziani in acknowledgement of her hospitality and assistance during fieldwork.

Occurrence: Ferrière-Larçon, Pauvrelay (Paulmy commune), Indre-et-Loire, France; faluns of Middle Miocene age.

Material: Holotype MNHN A25733: left scutum. Paratypes: MNHN A25734 left tergum; MNHN A25735–A25736 and A25742–25743 laterals; MNHN A25737 and A25740–25741 rostro-laterals; MNHN A25738 rostrum; MNHN A25739 carina.

In addition to the type series, other numerous unregistered plates from the type localities are at my disposal.

Measurements: Holotype MNHN A25733: occludent margin 2.0 mm, articular margin 1.1 mm. Paratype: MNHN A25734: articular margin 1.5 mm. Paratype: MNHN A25735: height of middle of the plate 1.45 mm, basal margin 1.8 mm. Paratype: MNHN A25737: height of middle of the plate 1.4 mm, basal margin 1.4 mm. Paratype: MNHN A25739: height of middle of the plate 1.3 mm. Paratype: MNHN A25738: height of middle of the plate 0.9 mm. Paratype: MNHN A25736: height of middle of the plate 1.9 mm, basal margin 2.7 mm. Paratype: MNHN A25740: height of middle of the plate 1.6 mm. Paratype: MNHN A25741: height of middle of the plate 1.4 mm. Paratype: MNHN A25742: height of middle of the plate 1.15 mm. Paratype: MNHN A25743: height of middle of the plate 1.5 mm.

Description: Wall plates thin, external surface of parietes smooth (with some protuberances when viewed under SEM), internal surface with small pores, generally red grey; radii very narrow with oblique summits; alae broad with secondary alar increment.

Scutum isoscelene triangular with tergal margin much shorter than other margins, thin; externally fine close growth ridges distinct on uneroded portions; articular ridge medial, low, not extending beyond scutal margin; articular furrow shallow; adductor muscle ridge short, low; pit for adductor muscle long, oval, deep, near occludent margin; pit for depressor muscle lacking.

Tergum narrow, club-shaped; externally convex, with fine growth ridges; articular ridge high, not reflexed; articular furrow shallow; carinal lobe narrow, few short crests for the depressor muscle; spur lacking.

Affinities: Chthamalus grazianii sp. nov. differs from C. stellatus in having a scutum much longer than broad with an apex forming an angle less than 90°. It shares these characters with C. montagui but differs from this species in having no lateral depressor muscle pit and a very slight trace of an adductor ridge. It differs from both species in having a club-shaped tergum. Chthamalus grazianii sp. nov. differs from C. ligusticus in having compartments which are not divided into 2 or 3 by broad longitudinal sulci.

Figures

FIGURE 1. Chthamalus grazianii sp. nov., external and internal side of plates: 1 a, b, scutum, holotype MNHN A 25733; 2 a, b, tergum, paratype MNHN A 25734; 3 a, b, 4, 8, 9, laterals, paratypes MNHN A 25735, MNHN A 25736, MNHN A 25742, MNHN A 25743; 5 a, b, 10, 11, rostro-laterals, paratypes MNHN A 25737, MNHN A 25741, MNHN A 25740; 6 a, b, rostrum, paratype MNHN A 25738; 7 a, b, carina, MNHN A 25739.