Tyto richae, Pavia & Manegold & Haarhoff, 2015

Pavia, Marco, Manegold, Albrecht & Haarhoff, Pippa, 2015, New early Pliocene owls from Langebaanweg, South Africa, with first evidence of Athene south of the Sahara and a new species of Tyto, Acta Palaeontologica Polonica 60 (4), pp. 815-828 : 817-820

Tyto richae sp. nov.

Fig. 1 .

Etymology: Dedicated to Patricia Vickers-Rich, who carried out the preliminary analysis of the Langebaanweg avifauna in 1980 and who has contributed significantly to the record of African fossil birds.

Type material: Holotype: right tarsometatarsus, SAM-PQ-L50354 B, distal end . Paratypes: left coracoid, SAM-PQ-L23436 , complete; left ulna, SAM-PQ-L50411 L, distal end; left tibiotarsus, SAM-PQL28197 AU, distal end; left tibiotarsus, SAM-PQ-L50022 ZA, distal end; right tibiotarsus, SAM-PQ-L50022 ZB, distal end .

Type horizon: Muishond Fontein Pelletal Phosphorite Member of the Upper Varswater Formation; early Pliocene ( Hendey 1974, 1981; Roberts et al. 2011).

Type locality: Langebaanweg , South Africa .

Referred material. —Right coracoids, SAM-PQ-L30104, cranial end; right tarsometatarsus, SAM-PQ-L28199DT, distal end; right pedal phalanx III/2, SAM-PQ-L56207G; terminal pedal phalanges, SAM-PQ-L56212 A and F.

Diagnosis. —Medium-sized species of Tyto , distinctly larger than T. alba , coracoid relatively slender showing a wellmarked facies articularis clavicularis with a tuberculum on its ventral side, and tarsometatarsus with the trochlea III protruding more distally than the trochlea II and IV.

Description.— Tyto richae sp. nov. is described on the basis of eleven more or less fragmentary bones that show a combination of characters previously described as being diagnostic for Tyto and which allow the distinction between this genus and Phodilus as well as other Tytonidae ( Mourer-Chauviré 1987; Pavia 2004; Pavia and Mourer-Chauviré 2011; Göhlich and Ballmann 2013). In particular, coracoid: (i) tuberculum brachiale absent, (ii) processus procoracoideus short and wide at its base, (iii) cranial part of sulcus musculi supracoracoidei not pneumatised, (iv) shaft ventro-dorsally flattened, (v) processus lateralis wide in cranial view; ulna: (vi) condylus dorsalis ulnaris oblique in ventral view, (vii) condylus ventralis ulnaris pointed and distally well developed; tibiotarsus: (viii) distal part of sulcus extensorius shallow, (ix) condyli caudally extended forming a square angle with the shaft, (x) condyli of similar thin shape in distal view; tarsometatarsus: (xi) trochlea metatarsi III protruding more distally than the remaining trochleae, (xii) medial groove on trochlea metatarsi III limited to the distal part, (xiii) distal edge of trochlea metatarsi IV wide and distally concave in lateral view; pedal phalanx III/2: (xiv) not as shortened as in Strigidae with blunt rather than pointed dorsoproximal process.

Tyto richae sp. nov. is larger than T. a. alba , T. a. guttata, and T. a. ernesti (see Louchart 2002) the extant European subspecies of cosmopolitan T. alba , which lack sexual size dimorphism, and also exceeds T. a. affinis of sub-Saharan Africa in size ( König and Weick 2008) ( Tables 1–3). The new Tyto species is similar-in-size to the few T. capensis available for comparison, but has stouter coracoid and hind limb bones. Tyto richae sp. nov. is larger than T. sanctialbani and slightly larger than T. campiterrae , but smaller than T. balearica and other palaeospecies of Tyto described from Europe and North America ( Mourer-Chauviré et al. 1980; Louchart 2002; Pavia 2004; Pavia and Mourer-Chauviré 2011).

The coracoid of Tyto richae sp. nov. is more slender than in T. sanctialbani , T. balearica , and T. campiterrae , thus more similar in structure to that of T. alba , and is stouter than in T. capensis ( Table 1). The cranial end of the coracoid in the new species is characterized by a well developed facies articularis clavicularis, with an irregular surface that terminates ventrally into a tuberculum. The facies articularis sternalis is narrower than in T. alba and T. sanctialbani . Compared to T. alba , the condylus ventralis ulnae of T. richae sp. nov. does not protrude as far ventrally and the incisura tuberculi carpalis is less marked. In cranial view, the distal tibiotarsus of Tyto richae sp. nov. is characterized by a small crest proximal to the medial side of the condylus lateralis. A similar crest is also present in T. sanctialbani , but is absent in all the other Tyto species, both fossil and extant. The caudal side of the condylus medialis is wider than in T. alba , and the depression situated proximally to the trochlea cartilaginis tibialis is not deep as in other Tyto species, both living and fossil. The two condyli are similar in size and shape and the incisura intercondylaris is proportionately wider than in T.

Horizon Specimen SAM-PQ-L23436, SAM-PQ-L28197AU, Langeberg Quartz SAM-PQ-L28199DT, SAM-PQ-L50022ZA, Sand Member SAM-PQ-L50022ZB, SAM-PQ-L56207G, SAM-PQ-L56212A, SAM-PQ-L56212F Muishond Fontein SAM-PQ-L30104, SAM-PQ-L50354B, Pelletal Phosphorite SAM-PQ-L50411L Member alba . Although only the distal part of the tarsometatarsus of the new species is known, this bone is apparently stouter than that of T. capensis , T. alba , and T. campiterrae ( Table 2). The trochlea metatarsi III extends further distally than the other trochleae, as is the case with T. sanctialbani , but not as in other Tyto species. The fossil pedal phalanx III/2 is larger and more robust than the corresponding bone of T. alba and it is stouter with larger epiphyses than T. capensis ( Table 3). The terminal pedal phalanges are compatible to the other referred material to T. richae sp. nov. They are only slightly curved and equipped with a proximodistally elongated processus extensorius as is typical for Strigiformes in general ( Ballmann 1973). The processus flexorius is very small in both specimens as is the case with Tytonidae ( Ballmann 1973) .

Measurements. —Right distal tarsometatarsus SAM-PQL50354B (holotype): distal width 12.7 mm, distal depth> 9.5 mm; for additional measurements, see Tables 1–3.

Stratigraphic and geographical range.—Langeberg Quartz Sand Member and Muishond Fontein Pelletal Phosphorite Member of the UpperVarswater Formation at Langebaanweg, early Pliocene of South Africa ( Table 4).

Figures

Fig.1.Tytonid owl Tyto richae sp.nov.from the early Pliocene, Upper Varswater Formation at Langebaanweg, SouthAfrica; paratypes (A–C, E), holotype (D). A. Left ulna (SAM-PQ-L50411 L), in dorsal (A1), caudal (A2), ventral (A3), and cranial (A4) views. B. Left coracoid (SAM-PQ-L23436), in dorsal (B1), lateral (B2), medial (B3), and ventral (B4) views. C. Left tibiotarsus (SAM-PQ-L28197 AU), in cranial (C1), lateral (C2), caudal (C3), medial (C4), and distal (C5) views. D. Right tarsometatarsus (SAM-PQ-L50354 B), in dorsal (D1), lateral (D2), plantar (D3), medial (D4), and distal (D5) views. E. Left tibiotarsus (SAM-PQ-L50022 ZA), in cranial (E1), lateral (E2), caudal (E3), medial (E4), and distal (E5) views.