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Prosobonia sauli sp. nov. (1 Viewer)

Fred Ruhe

Well-known member
Vanesa L. De Pietri, Trevor H. Worthy, R. Paul Scofield, Theresa L. Cole, Jamie R. Wood, Kieren J. Mitchell, Alice Cibois, Justin J. F. J. Jansen, Alan J. Cooper, Shaohong Feng, Wanjun Chen, Alan J. D. Tennyson & Graham M. Wragg, 2020

A new extinct species of Polynesian sandpiper (Charadriiformes: Scolopacidae: Prosobonia) from Henderson Island, Pitcairn Group, and the phylogenetic relationships of Prosobonia

Zoological Journal of the Linnean Society. Online edition. doi:10.1093/zoolinnean/zlaa115

Abstract: https://academic.oup.com/zoolinnean...nnean/zlaa115/5959945?redirectedFrom=fulltext

We describe a new species of Polynesian sandpiper from Henderson Island, Prosobonia sauli sp. nov., based on multiple Holocene fossil bones collected during the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands (1991–92). Prosobonia sauli is the only species of Prosobonia to be described from bone accumulations and extends the record of known extinct Polynesian sandpipers to four. It is readily differentiated from the extant Tuamotu Sandpiper P. parvirostris in several features of the legs and bill, implying ecological adaptations to different environments. The geographically nearest Prosobonia populations to Henderson Island were found on Mangareva, where it is now extinct. A previous record of a species of Prosobonia from Tubuai, Austral Islands, is here shown to belong to the Sanderling Calidris alba. Our analyses of newly sequenced genetic data, which include the mitochondrial genomes of P. parvirostris and the extinct Tahiti Sandpiper P. leucoptera, confidently resolve the position of Prosobonia as sister-taxon to turnstones and calidrine sandpipers. We present a hypothesis for the timing of divergence between species of Prosobonia and other scolopacid lineages. Our results further provide a framework to interpret the evolution of sedentary lineages within the normally highly migratory Scolopacidae.

Keywords: molecular clocks, molecular phylogeny, island fauna, Pacific Islands, palaeobiogeography, Caenozoic, fossil record, Quaternary, palaeoecology, extinction


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Well-known member
Type locality and age: Henderson Island, North Beach (east end), Site # Hen 6 (3 mm), collected from a cave in cliff (12–25 m elevation); Holocene. See Wragg (1995b).

Etymology: The species is named for Edward (Ed) K. Saul, a Cook Island-based ornithologist and conservationist. For the last 30 years Ed has contributed hugely to saving the ‘Kakerori’, Rarotonga Monarch Pomarea dimidiata (Hartlaub & Finsch, 1871) from extinction.

Diagnosis: Small scolopacid wader, about the size of Prosobonia parvirostris, with bill straight and premaxilla twice wider (mediolaterally) than deep (dorsoventrally) at the level of rostral side narial opening (Fig. 5A–C); elongated legs, tarsometatarsus (Fig. 5AA–D D) with relatively large foramen vasculare distale, prominent plantar projection of the trochlea metatarsi I

Fred Ruhe

Well-known member
Systematic palaeontology
Aves Linnaeus, 1758
Charadriiformes Huxley, 1867
Scolopacidae Rafinesque, 1815

A combination of several postcranial features, primarily of the humerus, coracoid and tarsometatarsus, allow scolopacids to be distinguished from other charadriiform family-group taxa. These features have been assessed by some authors (most recently by, for example: Strauch, 1978; Mayr, 2011; De Pietri & Mayr, 2012; De Pietri et al., 2016) and, for example, for the humerus, the combination of the presence of a dorsal fossa pneumotricipitalis, a ridge transversing the incisura capitis, a proximodistally elongated tuberculum dorsale, a dorsoventrally narrow impressio coracobrachialis, a distinct fossa musculi brachialis and a well-developed and protruding processus supracondylaris dorsalis, is unique to scolopacids and allows unambiguous referral of the Henderson bones to this family.

Prosobonia Bonaparte, 1850

The Henderson bones can be attributed to Prosobonia and no other genus within Scolopacidae based on the following combination of features: humerus with fossa pneumotricipitalis dorsalis dorsoventrally wide (wider than ventral fossa), crista deltopectoralis only just surpassing distally crista bicipitalis, crista bicipitalis straight, tip of processus supracondylaris dorsalis with distinct proximal orientation; ulna with tubercle proximal of incisura tendinosa prominent dorsally; carpometacarpus with wide spatium intermetacarpale; femur with prominent tuberculum musculi gastrocnemialis lateralis, wellmarked impressiones ansae musculi iliofibularis and cranially salient medial crest of sulcus patellaris; tarsometatarsus with trochlea metatarsi II flaring medially, noticeable widening of shaft distally; sternum with spina externa rostrally extended, bifurcated tip that projects dorsally, pars cardiaca shallow, incisurae laterales reduced (not preserved in Henderson specimens).

Prosbonia sauli sp. nov. De Pietri, Worthy, Scofield, and Wragg
Zoobank registration: urn:lsid:zoobank. org:act:19451CFF-D425-4B8C-B288-B6191390971E

Holotype: The left tarsometatarsus in lot NHMUK S/2001.35.26 (Fig. 5 AA–DD). It is in near excellent condition, with some minor damage to lateral margin of proximal end. NHMUK S/2001.35.26 also includes a right cranial portion of a scapula, a right radius broken in three parts and a left carpometacarpus missing the os metacarpale minus. These elements do not necessarily represent the same individual as the holotype tarsometatarsus and so are considered as referred material for the new taxon.

For the type locality and age, etymology and diagnosis see the contribution of Melanie (#3 of this thread)

Differential diagnosis: Differs from P. parvirostris in the shape of premaxilla (Fig. 6A, B), being straighter and proportionally wider, leg bones proportionally longer, tuberculum ventrale on humerus rounded instead of flat, ulna with impressio brachialis proportionally more elongated and tubercle bordering incisura tendinosa not as pronounced, processus extensorius of carpometacarpus more slender and elongated, and proximal and distal synostoses proportionally more elongated, tibiotarsus straight not medially concave, tarsometatarsus with sulcus for the tendon for the musculus flexor hallucis longus shallower and more laterally positioned, sulcus for tendon of musculus flexor perforatus digiti 2 deeper and better marked, foramen vasculare distale proportionally larger, plantar projection of trochlea metatarsi II more prominent and incisura intertrochlearis lateralis wider. Differs from P. cancellata in having proportionally longer legs (assuming P. parvirostris and P. cancellata are similar in leg length, as there is no evidence of the contrary despite the hind toe being presumably shorter in P. cancellata; Walters, 1993; Jansen & Cibois, 2020). Differs tentatively from P. ellisi in having a straighter bill (see: Walters, 1991). Differs from P. leucoptera in having a mediolaterally wider and dorsoventrally deeper tip of the bill, carpometacarpus with proximodistally more elongated synostosis metacarpalis distalis and only slightly more elongated legs that are possibly not as stout – all three complete tarsometatarsi are at least 2 mm longer than measured for P. leucoptera.

Abreviations: d=distal; p=proximal; R=right; L=left.

Material: NHMUK S/2001.35.1 (dR humerus, dR ulna); NHMUK S/2001.35.2 (dR humerus); NMH S/2001.35.4 (left carpometacarpus); NHMUK S/2001.35.6 (2R, 1L phalanx proximalis digiti majoris); NHMUK S/2001.35.7 [dR radius, L humerus missing proximal end, dR ulna, dL carpometacarpus, L tibiotarsus (subadult)]; NHMUK S/2001.35.8 [L tarsometatarsus (subadult)]; NHMUK S/2001.35.9 (cranial portion of sternum, dR tibiotarsus); NHMUK S/2001.35.10 (dR tibiotarsus); NHMUK S/2001.35.11 (dL tarsometatarsus, R phalanx proximalis digiti majoris); NHMUK S/2001.35.12 (L ulna, R carpometacarpus); NHMUK S/2001.35.13 (R scapula, L scapula, cranial portion of sternum, premaxilla, R humerus, R carpometacarpus); NHMUK S/2001.35.14 [L humerus missing proximal end, L carpometacarpus missing distal end (subadult)]; NHMUK S/2001.35.15 (cranial portion of sternum, R carpometacarpus, L tarsometatarsus); NHMUK S/2001.35.16 (dR tarsometatarsus); NHMUK S/2001.35.17 (L carpometacarpus); NHMUK S/2001.35.18 (R femur in two parts, pR tarsometatarsus); NHMUK S/2001.35.19 (dR femur, pR carpometacarpus); NHMUK S/2001.35.20 (dR femur, pL femur, dL humerus, L phalanx proximalis digiti majoris); NHMUK S/2001.35.21 (subadult, likely one individual, L/R humerus, R ulna, L radius, L/R carpometacarpus, L phalanx proximalis digiti majoris, L femur, L/R tibiotarsus, two pedal phalanges); NHMUK S/2001.35.22 (L cranial scapula); NHMUK S/2001.35.23 (fragmentary synsacrum); NHMUK S/2001.35.24 (dR tibiotarsus); NHMUK S/2001.35.26 (R cranial scapula, R radius in three parts, L carpometacarpus, L tarsometatarsus).


Figure 1. Prosobonia sauli sp. nov. from Henderson Island. A–C, premaxilla (NHMUK S/2001.35.13) in dorsal (A), ventral (B) and side (C) views. D–E, sternum (NHMUK S/2001.35.15) in dorsal (D) and ventral (E) views. F–G, right scapula (NHMUK S/2001.35.13) in medial (F) and lateral (G) views. H–I, left carpometacarpus (NHMUK S/2001.35.26) in ventral (H) and dorsal (I) views. J–K, right humerus (NHMUK S/2001.35.13) in cranial (J) and caudal (K) views. L, left radius (NHMUK S/2001.35.21, subadult) in dorsal view; M–N, distal right radius (NHMUK S/2001.35.26) in dorsal (M) and distal (N) views. O–Q, left ulna (NHMUK S/2001.35.12) in ventrocranial (O), ventral (Q) and dorsal (Q) views. R, S, U, left femur (NHMUK S/2001.35.21, subadult) in caudal (R), cranial (S) and lateral (U) views; T, right femur (NHMUK S/2001.35.18) in caudal view. V–X, right tibiotarsus (NHMUK S/2001.35.21, subadult) in caudal (V), cranial (W) and distal (X) views; Y–Z, right tibiotarsus (NHMUK S/2001.35.10) in cranial (Y) and medial (Z) views. AA–DD, left tarsometatarsus (NHMUK S/2001.35.26, holotype) in plantar (AA), dorsal (BB), proximal (CC) and distal (DD) views. Abbreviations: acr, acromion; cb, crista bicipitalis; cdp, crista deltopectoralis; cdu, condylus dorsalis ulnae; ctd, cotyla dorsalis; ctv, cotyla ventralis; dep, depression; dfp, dorsal fossa pneumotricipitalis; fah, facies articularis humeralis; fmb, fossa musculi brachialis; fvd, foramen vasculare distale; iacd, impressio ansae m. iliofibularis (pars caudalis); pex, processus extensorius; pc, pars cardiaca (sternum); pptII, plantar projection on trochlea metatarsi II; psd, processus supracondylaris dorsalis; pst, pons supratendineus; rid, ridge; sac, sulcus articularis coracoideus; sim, spatium intermetacarpale; sp, sulcus patellaris; spe; spina externa (sternum); st, sulcus tendinosus (ulna); tbc, tuberculum coracoideum; tc, tuberculum carpale; tgl, tuberculum m. gastrocnemialis lateralis; tmt II, trochlea metatarsi II; trel, tuberculum retinaculi m. fibularis lateralis; tub, tubercle delimiting incisura tendinosa (ulna); tub (tst), tuberculum m. scapulotricipitis; tv, tuberculum ventrale. Scale bars equal 0.5 mm except for A–C, which is 0.1 mm. M–N, P–Q, T–U, X–Z, CC–DD not to scale.


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Björn Bergenholtz

... also known as "Calalp"
• the extinct Henderson (Island) Sandpiper Prosobonia sauli De Pietri, et al., 2020

De Pietri, V. L., T. H. Worthy, R. P. Scofield, T. L. Cole, J. R. Wood, K. J. Mitchell, A. Cibois, J. J. F. J. Jansen, A. J. Cooper, S. Feng, W. Chen, A. J. D. Tennyson & G. M. Wragg. 2020. A new extinct species of Polynesian sandpiper (Charadriiformes: Scolopacidae: Prosobonia) from Henderson Island, Pitcairn Group, and the phylogenetic relationships of Prosobonia. Zoological Journal of the Linnean Society, 20, pp: 1–26.

Accessible, in full, at ResearchGate (here)

And, regarding Melanie's question:
It might be interesting to know whether it became extinct before or after 1500.
See the following part:
... . The Henderson Sandpiper became extinct possibly early during human occupation (Wragg, 1995b), which revised estimates suggest occurred no earlier than the 11th century AD (Wilmshurst et al., 2011; Anderson et al., 2019). ...

[from Page 21]

And regarding my own favorite subject:
Etymology: The species is named for Edward (Ed) K. Saul, a Cook Island-based ornithologist and conservationist. For the last 30 years Ed has contributed hugely to saving the ‘Kakerori’, Rarotonga Monarch Pomarea dimidiata (Hartlaub & Finsch, 1871) from extinction.

[from Page 13]

The commemoration itself is fairly obvious; aimed at the following Conservation Champion:

• "Edward (Ed) K. Saul", a k a 'Eddie' or 'Papa Ed' (see; here or/alt. here).


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