Amphithyris seminula ( Philippi, 1836 )

Nauendorf, Alice, Wörheide, Gert & Lüter, Carsten, 2014, Revision of the brachiopod genus Amphithyris (Rhynchonelliformea: Platidiidae) with descriptions of two new species, Zootaxa 3847 (2), pp. 221-240 : 230

Amphithyris seminula ( Philippi, 1836)

( Fig. 5 ; Table 4 )

Terebratula seminulum Philippi, 1836 : p. 97, pl. 6, fig. 15a–g (original description); 1844: p. 69 (erroneously synonymized with Orthis neapolitana (Scacchi) (= Joania cordata (Risso, 1826)) — Costa, 1852: p. 38 (erroneously synonymized with Orthis neapolitana (Scacchi) (= Joania cordata (Risso, 1826)) — Davidson, 1852a: p. 371 (as Morrisia seminulum , new combination); 1852b: p. 81 (erroneously synonymized with Argiope neapolitana (Scacchi) (= Joania cordata (Risso, 1826)) ; 1887: p. 152 (erroneously synonymized with Platydia [sic!] anomioides (Scacchi & Philippi in Philippi, 1844))—de Monterosato 1879: p. 307, pl. 13, fig. 3 (as Platidia seminulum , new combination)— Fischer & Oehlert 1891: p. 99 (as Platidia seminulum )— Thomson 1918: p. 21 (as Amphithyris seminula , new combination); 1927: p. 216— Dall 1920: p. 332 (as Platidia seminula )— Atkins 1959: p. 125 (suggestion that T. seminulum is a juvenile Platidia anomioides , to be left undecided until type material is found)— Logan 1979: p. 63— Lüter & Sieben 2005: p. 185 (identification of possible type material)— MacKinnon et al. 2008: p. 324, fig. 4 A–I (taxonomic status confirmed, investigation of additional historical material)

Orthis anomioides Scacchi & Philippi in Philippi, 1844: p. 69, pl. 18, fig. 9 (erroneously synonymized with Platidia seminulum , new combination by Dall 1920: p. 332)

Type material. Lectotype: ZMB Bra 2146; Paralectotype: ZMB Bra 1675

Type locality. Trapani, Sicily, Mediterranean Sea.

Material examined. Lectotype: ZMB Bra 2146; Paralectotype: ZMB Bra 1675

Diagnosis. Shell planoconvex, flat dorsal valve with low median septum. Capillae absent.

Description. Shell planoconvex, oval to round. Dorsal valve almost flat, slightly convex from posterior to foramen ( Fig. 5 B). Very low median septum, highest point mid-valve or below mid-valve ( Fig. 5 A). Two curved, very low ridges on each side of valve underlie the lophophore ( Fig. 5 B). Short socket ridges ( Fig. 5 C). Ventral valve with hinge teeth beak-like, not parallel to hinge line ( Fig. 5 D and E). Valve exterior smooth with growth lines ( Fig. 5 F).

Remarks. Two specimens of A. seminulum were found in the brachiopod collection of the Museum für Naturkunde Berlin in a glass tube together with an old label (not Philippi´s handwriting) saying " Terebratula seminulum Ph., Sicilia, Dr. Ph. ". The tube contains a mixture of species with the second species identified as Joania cordata . Lüter & Sieben (2005) proposed that Philippi´s figures of T. seminulum belong to two different species, Platidia anomioides (Scacchi & Philippi) (Philippi´s fig. 15a–d) and Joania cordata (Risso) (Philippi´s fig. 15e–g). This potential mixture of two species in the original material of Philippi was already discussed by Atkins (1959). Based on a comparison with Fig. 4 of MacKinnon et al. (2008) (material from the Davidson Collection, NHM, London) demonstrating that T. seminulum is not an immature stage of P. anomioides , the two specimens in the Berlin material previously identified as P. anomioides by Lüter & Sieben (2005) were assigned to A. seminula . We further identified this material as the original type series collected by Philippi and therefore designate ZMB Bra 2146 as lectotype and ZMB Bra 1675 as paralectotype of Amphithyris seminula ( Philippi, 1836) .

Figures

FIGURE 4. Amphithyris parva MacKinnon, Hiller, Long & Marshall, 2008. A – F. Paratype NMNZ Br 1069. A. Dorsal valve interior showing absence of median septum. B. Close-up of dorsal interior with large amphithyrid foramen. C. Dorsal valve exterior with weak capillae. D. Ventral valve interior. E. Close-up ventral valve interior showing long straight hinge line. F. Ventral exterior with weak capillae. Scale bars = 200 µm.

FIGURE 5. Amphithyris seminula (Philippi, 1836). Sicily, Mediterranean Sea. A – B. Paralectotype ZMB Bra 1675. A. Dorsal valve interior with low median septum. B. Lateral view of dorsal valve. C – F. Lectotype ZMB Bra 2146. C. Close-up of dorsal valve interior with short socket ridges. D. Ventral valve interior. E. Close-up of ventral valve interior showing beak-like hinge teeth. F. Lateral view of ventral valve, showing smooth surface. Scale bars = 200 µm.