Type specimens of birds in the Natural History Museum, University of Oslo, Norway Author Johannessen, Lars Erik Natural History Museum, University of Oslo, PO Box 1172 Blindern, NO- 0318 Oslo, Norway Author Lifjeld, Jan T. 0000-0002-9172-9985 Natural History Museum, University of Oslo, PO Box 1172 Blindern, NO- 0318 Oslo, Norway & j. t. lifjeld @ nhm. uio. no; https: // orcid. org / 0000 - 0002 - 9172 - 9985 j.t.lifjeld@nhm.uio.no text Zootaxa 2022 2022-06-09 5150 4 451 486 journal article 69152 10.11646/zootaxa.5150.4.1 9f4f4dd6-92eb-4946-b5a4-2fe994807894 1175-5326 6626759 7A36C3D5-765A-43E8-BA3F-68C51253B3A0 Catharacta skua hamiltoni Hagen, 1952 Birds of Tristan da Cunha . Results of the Norwegian scientific expedition to Tristan da Cunha 1937–1938, No. 20: 135–145. Current name: Stercorarius antarcticus hamiltoni ( Hagen, 1952 ) Syntype NHMO-BI-67601 [I026282]; Study skin; Imm. F; Yngvar Hagen (80), 31 January 1938 ; SHN 2 : Nightingale; 37.427° S , 12.478° W ; 13a. Syntype NHMO-BI-67602 [I026283]; Study skin; Ad. M; Yngvar Hagen (260), 26 February 1938 ; SHN: Inaccessible; 37.300° S 12.673° W ; 13b. Syntype NHMO-BI-67603 [I026284]; Study skin; Juv. F; Yngvar Hagen (57), 20 January 1938 ; SHN: Inaccessible; 37.300° S 12.673° W ; 13c. Syntype NHMO-BI-67604 [I026285]; Study skin; Ad. M ; Yngvar Hagen (3), 16 December 1937 ; SHN: Tristan da Cunha ; 37.105° S 12.278° W ; 14a. Syntype NHMO-BI-67605 [I026286]; Study skin; Ad. F ; Yngvar Hagen (75), 25 January 1938 ; SHN: Tristan da Cunha ; 37.105° S 12.278° W ; 14b. Syntype NHMO-BI-85384; Study skin; Ad. F ; Yngvar Hagen (2), 16 December 1937 ; SHN: Tristan da Cunha ; 37.105° S 12.278° W ; 14c. Syntype NHMO-BI-92659; Blown eggshell; Egg ; Yngvar Hagen (352), 1937; SHN: Tristan da Cunha ; 37.105° S 12.278° W ; 5a. Syntype NHMO-BI-92660; Blown eggshell; Egg ; Yngvar Hagen (356), 1937; SHN: Tristan da Cunha ; 37.105° S 12.278° W ; 5b. Syntype NHMO-BI-92661; Blown eggshell; Egg ; Yngvar Hagen (353), 1937; SHN: Tristan da Cunha ; 37.105° S 12.278° W ; 5c. Syntype NHMO-BI-92662; Blown eggshell; Egg ; Yngvar Hagen (357), 1937; SHN: Tristan da Cunha ; 37.105° S 12.278° W ; 5d. Syntype NHMO-BI-92663; Blown eggshell; Egg ; Yngvar Hagen (358), 1937; SHN: Tristan da Cunha ; 37.105° S 12.278° W ; 5e. Syntype NHMO-BI-92664; Blown eggshell; Egg ; Yngvar Hagen (355), 1937; SHN: Tristan da Cunha ; 37.105° S 12.278° W ; 5f. Syntype NHMO-BI-92665; Blown eggshell; Egg ; Yngvar Hagen (354), 1937; SHN: Tristan da Cunha ; 37.105° S 12.278° W ; 5g . Syntype NHMO-BI-92666; Blown eggshell; Egg ; Yngvar Hagen (351), 1937; SHN: Tristan da Cunha ; 37.105° S 12.278° W ; 5h. Syntype NHMO-BI-92668; Blown eggshell; Egg ; Yngvar Hagen (350), 1937; SHN: Tristan da Cunha ; 37.105° S 12.278° W ; 5i. Remarks: Hagen (1952) based his description of this subspecies on a total of nine birds examined in the field, but only six of them were skinned and preserved. He did not assign any holotype among these, and all nine birds must therefore be considered syntypes . In addition, he also explicitly mentioned and provided average measurements for nine eggs . According to Article 72.5.1 of the Code ( International Commission on Zoological Nomenclature 1999 ), ’…any part of an animal… ’ is eligible to be a name-bearing type, and we therefore consider also these nine eggs to be part of the type series for this taxon. Dimensions of all nine eggs , based on measurements made by L.E.J., are provided in Table 3 ; the average dimensions of these (50.6 x 69.7 mm ) match exactly those provided by Hagen (1952) . All extant syntypes (i.e. six skins and nine eggs ) are present in the NHMO collection. TABLE 3. Dimensions of the nine eggs included in the type series of Stercorarius antarcticus hamiltoni Hagen, 1952 , based on measurements taken by the authors (L.E.J.).

Catalogue number	Field no.	Width (mm)	Length (mm)
NHMO-BI-92668	350	49.7	74.2
NHMO-BI-92666	351	50.2	70.0
NHMO-BI-92659	352	52.8	69.6
NHMO-BI-92661	353	50.2	71.1
NHMO-BI-92665	354	50.5	67.1
NHMO-BI-92664	355	52.4	68.5
NHMO-BI-92660	356	49.8	70.2
NHMO-BI-92662	357	49.9	65.8
NHMO-BI-92663	358	50.1	70.8
Average	50.6	69.7

2 SHN: Saint Helena, Ascension and Tristan da Cunha FIGURE 4. Labels (metal tags) of type specimens in the NHMO Bird Collection of Catharacta skua hamiltoni Hagen, 1952 (all collector’s labels). a) NHMO-BI-67601; b) NHMO-BI-67602; c) NHMO-BI-67603; d) NHMO-BI-67604; e) NHMO-BI-67605; f) NHMO-BI-85384. The skins are all labelled with metal tags with the collector’s field number embossed into them ( Figure 4 ), while the eggs are labelled with the field number written with pencil directly on their surface ( Figure 5 ). One of the eggs (NHMO-BI-92664) is cracked and has previously been attempted to be repaired.