Patriarchus leptocephalus Ameghino, 1891

Fernández, Mercedes, Fernicola, Juan Carlos, Cerdeño, Esperanza & Reguero, Marcelo A., 2018, Identification of type materials of the species of Protypotherium Ameghino, 1885 and Patriarchus Ameghino, 1889 (Notoungulata: Interatheriidae) erected by Florentino Ameghino, Zootaxa 4387 (3), pp. 473-498 : 492-493

Patriarchus leptocephalus Ameghino, 1891

Holotype. MACN-A 3989 ( Figs. 4 A–B ), almost complete skull.

Paratype. MACN-A 3990, left cranial fragment with complete I1 –M3 series, and MACN-A 3991, complete left mandibular ramus with i1 –m3 series, both of the same individual.

Diagnosis ( Ameghino 1891: 293). “ Tamaño pequeño, pero poco mayor aun que el de la especie precedente [ Patriarchus diastematus ]. Frontales muy angostos; hocico angosto y prolongado; paladar muy angosto adelante. Toda la forma del cráneo angosta y prolongada. Longitud del cráneo, 82 milímetros; ancho interorbital de los frontales, 21 milímetros; longitud de los frontales sobre la línea media, 21 milímetros. Adelante, los frontales penetran un poco entre los nasales ”.

English translation. Species of small size, but slightly larger than the previous species [ Patriarchus diastematus ]. Frontals are very narrow; snout is narrow and long; palate very narrow anteriorly. The whole skull is narrow and long. Length of the skull, 82 millimetres; interorbital width of the frontals, 21 millimetres; length of the frontals on the midline, 21 millimetres. Anteriorly, the frontals slightly penetrate the nasals.

Comments. Ameghino (1891) described this taxon without illustrating any specimens of it. According to Ameghino’s catalogue the skull MACN-A 3989 is the type of this species, whereas both incomplete skull MACN- A 3990 and mandible MACN-A 3991 are indicated each as “ tipo 2° ” (2nd type), an old and informal term used to refer to a paratype (C. Sciosia, pers. comm.). Mones (1986) also indicated MACN-A 3989 to MACN-A 3991 as the type specimens of the species, but did not make a distinction between type and 2nd type. The skull MACN-A 3989 matches the original diagnosis as it is slightly larger (length of P2–M3 = 30.2 mm) than the holotype of Pa. diastematus (length of P2–M3 = 28.1 mm), the frontals penetrate the nasals, the rostrum is long and the palate is anteriorly narrow; and almost all the measurements (length of the skull = 83.45 mm; intraorbital width of the frontals = 22 mm) also match those given by Ameghino (1891). Just the length of the frontals on the middle line (31 mm) is greater than the length (21 mm) provided by the author. Nevertheless, this was likely a typing error, because Ameghino established that the frontals were ‘very narrow’, which is contradictory with the same measure indicated for both the width and length of the frontals (21 mm). MACN-A 3990 is not complete enough to take any of the measurements given by Ameghino, but it cannot be discarded as part of the paratype, because it does not contradict the diagnosis and the author recognised this specimen as 2nd type when he acknowledged MACN-A 3989 as type in his catalogue. As MACN-A 3991 is a partial mandible of the same individual as MACN-A 3990, it is also recognised in this contribution as part of the paratype of Pa. leptocephalus . Regarding the remaining ten specimens assigned to the species in Ameghino’s catalogue, MACN-A 9653 is a cranial element, but only the length of the skull (83 mm) resembles Ameghino’s (1891) diagnosis, so it is discarded as part of the type series. The other nine catalogued materials are fragmented mandibles and, consequently, discarded as the type specimens; among them, only MACN-A 11191 is currently within the collection.

In summary, MACN-A 3989 is confirmed as the holotype of Pa. leptocephalus and the individual MACN-A 3990 plus MACN-A 3991 as the paratype of the species.

Chronological and geographical distribution of the type specimen. Santacrucian SALMA, Santa Cruz Province.

Figures

FIGURE 4. Patriarchus leptocephalus, holotype MACN-A 3989, incomplete skull, in ventral (A) and dorsal (B) views. Patriarchus altus, holotype MACN-A 4001, incomplete skull, in ventral (C) and dorsal (D) views. Patriarchus icochiloides, holotype MACN-A 4021, right maxillary fragment with alveolus of P1 and P2–M3, in occlusal view (E); holotype MACN-A 4022, right mandibular fragment with alveoli of p2–3 and p4–m3, in occlusal view (F). Scale bar = 10 mm.