Otus bikegila, Melo & Freitas & Verbelen & da Costa & Pereira & Fuchs & Sangster & Correia & de Lima & Crottini, 2022

Melo, Martim, Freitas, Barbara, Verbelen, Philippe, da Costa, Satiro R., Pereira, Hugo, Fuchs, Jerome, Sangster, George, Correia, Marco N., de Lima, Ricardo F. & Crottini, Angelica, 2022, A new species of scops-owl (Aves, Strigiformes, Strigidae, Otus) from Principe Island (Gulf of Guinea, Africa) and novel insights into the systematic affinities within Otus, ZooKeys 1126, pp. 1-54 : 1

Otus bikegila sp. nov.

Figs 2A , 8

Material.

Holotype. MHNC-UP-AVE7000: São Tomé and Príncipe • ♀, adult, moulting; Príncipe Island, South Príncipe, ca. 500 m NW of Ribeira Porco river mouth (Fig. 1 ); 1°33.03'N, 7°22.29'E; ca. 100 m a.s.l.; 29 May 2017; HP and Ceciliano do Bom Jesus leg.; skin prepared by Vanya Rohwer, skeleton prepared by Vanya Rohwer and Daniele Cataldo; left wing removed for wing mounting, all bones with the exception of the left tarso-metatarsus (tarsus) removed for skeleton preparation; Audio-recorded by HP (Xeno-canto audio: XC619445, XC619447 ; GenBank: 12S OM978880 , 16S OM978895 , ATP6 OM913485 , COI, OM937282 ; CYTB, OM937307 ; ND2, OM937351 ; ND3, ON016156 ; KIAA1239, OM937319 ; MYO2, OM937336 ; RAG1, ON016107 ; SACS, ON016118 ; TGFB2, ON016136 and TTN, ON016141 ; Gulf of Guinea database of MM: P7-04.

Diagnosis.

The new species (Figs 2 , 9 ) is assigned to the genus Otus based on genetic and morphological similarities to other known species of this genus. Phylogenetic analyses place it within the Afro-Palearctic clade, making generic placement unambiguous. Placement of the new species in Otus is further supported by its morphological characters: small size, distinctive ear-tufts, facial disc, short rounded wings, and short tail. The new species differs from the other described taxa of the Afro-Palearctic Otus clade ( O. hartlaubi , O. senegalensis , including O. s. feae sometimes treated as a distinct species, O. pembaensis , O. pamelae , O. scops , O. brucei ) by high genetic differentiation (pairwise ND2 distance ranging from 4.1% to 9.1%), by the lack of haplotype sha-ring at the KIAA1239 and TGFB2 nuclear markers, as well as from a combination of morphological, genetic and natural history (bioacoustics) traits.

We provide here a diagnosis relatively to the closely related species belonging to the Afro-Palearctic clade and also to O. ireneae due to the similarity in their calls. The diagnosis is based on the following analysed morphological characters: 1) Biwid; 2) Binares; 3) Tarlen; 4) Wilen; 5) Tailen); 6) SP10; 7) SP9; 8) SP4; on the following analysed bioacoustics characters: 9) F1; 10) F2; 11) F3; 12) F4; 13) F5; 14) F6; 15) F7; 16) F8; 17) DT1; 18) DT2; 19) DT4; 20) DF1; 21) DF2; 22) DFT1; 23) DFT2; and on the 24) list of diagnostic substitutions identified at the analysed nuclear mar-kers (Tables 1 - 4 ; Suppl. materials 12, 14).

In overall appearance, O. bikegila sp. nov. is most similar to O. hartlaubi from which it differs in one morphological and 10 bioacoustic characters: longer Wilen (145 to 151 mm vs. 130 to 139 mm), lower F1 (781.7 to 961.7 Hz vs. 1078.3 to 1360.0 Hz), lower F2 (933.3 to 1020.0 Hz vs. 1155.0 to 1285.0 Hz), lower F3 (980.0 to 1090.0 Hz vs. 1330.0 to 1478.3 Hz), lower F4 (950.0 to 1050.0 Hz vs. 1295.0 to 1483.3 Hz), lower F5 (931.7 to 1020.0 Hz vs. 1250.0 to 1418.3 Hz), lower F6 (976.7 to 1090.0 Hz vs. 1331.7 to 1480.0 Hz), lower F7 (1035.0 to 1106.7 Hz vs. 1407.5 to 1526.7 Hz), lower F8 (868.3 to 973.3 Hz vs. 1066.7 to 1267.5 Hz), shorter DT1 (0.231 to 0.248 s vs. 0.267 to 0.315 s), shorter DT4 (0.992 to 1.121 s vs. 9.181 to 15.998 s). Otus bikegila sp. nov. differs from O. hartlaubi also by the following molecular characters: KIAA (T vs. C in site 347); TTN (G vs. C in site 91); MYO2 (G vs. A in site 2); TGFB2 (C vs. A in site 28, G vs. A in site 33, G vs. T in site 47, T vs. C in site 99, A vs. G in site 178, G vs. T in site 305, C vs. G in site 369).

Otus bikegila sp. nov. differs from O. senegalensis senegalensis in seven morphological and one bioacoustic characters: higher Biwid (9.0 to 11.8 mm vs. 4.8 to 8.0 mm), larger Binares (11.3 to 12.6 mm vs. 8.0 to 12.5 mm), longer Tarlen (30.5 to 35.1 mm vs. 20.0 to 24.2 mm), longer Wilen (145 to 151 mm vs. 103 to 145 mm), longer Tailen (75 to 85 mm vs. 40 to 65 mm), longer SP10 (37 to 40 mm vs. 10 to 32 mm), longer SP9 (13 to 18 mm vs. 1 to 16 mm), lower F4 (950.0 to 1050.0 Hz vs. 1095.0 to 1236.7 Hz); and in the following molecular characters: TGFB2 (A vs. G in site 178, T vs. G in site 344).

Otus bikegila sp. nov. differs from O. senegalensis feae in one morphological and four bioacoustic characters: larger Biwid (9.0 to 11.8 mm vs. 6.4 to 6.8 mm), lower F2 (933.3 to 1020.0 Hz vs. 1132.5 to 1230.0 Hz), lower F7 (1035.0 to 1106.7 Hz vs. 1250.0 to 1357.5 Hz), shorter DT1 (0.231 to 0.248 s vs. 0.402 to 0.441 s), shorter DT4 (0.992 to 1.121 s vs. 7.127 to 7.479 s); and in the following molecular characters: KIAA (T vs. C in site 347, T vs. C in site 503); TGFB2 (A vs. G in site 178, T vs. C in site 285, G vs. C in site 392).

Otus bikegila sp. nov. differs from O. pembaensis in one morphological and nine bioacoustic characters: shorter SP4 (6 to 9.5 mm vs. 11 to 21 mm), higher F1 (781.7 to 961.7 Hz vs. 506.7 to 636.7 Hz), higher F2 (933.3 to 1020.0 Hz vs. 613.3 to 773.3 Hz), higher F3 (980.0 to 1090.0 Hz vs. 621.7 to 770.0 Hz), higher F4 (950.0 to 1050.0 Hz vs. 633.3 to 780.0 Hz), higher F5 (931.7 to 1020.0 Hz vs. 651.7 to 783.3 Hz), higher F6 (976.7 to 1090.0 Hz vs. 638.3 to 776.7 Hz), higher F7 (1035.0 to 1106.7 Hz vs. 660.0 to 790.0 Hz), higher F8 (868.3 to 973.3 Hz vs. 530.0 to 660.0 Hz), shorter DT4 (0.992 to 1.121 s vs. 5.043 to 7.570 s); and in the following molecular characters: TGFB2 (A vs. G in site 178, T vs. C in site 285, C vs. T in site 345).

Otus bikegila sp. nov. differs from O. pamelae in seven bioacoustic characters (morphology not analysed): lower F1 (781.7 to 961.7 Hz vs. 1031.7 to 1213.3 Hz), lower F2 (933.3 to 1020.0 Hz vs. 1111.7 to 1268.3 Hz), lower F4 (950.0 to 1050.0 Hz vs. 1096.7 to 1366.7 Hz), lower F5 (931.7 to 1020.0 Hz vs. 1083.3 to 1291.7 Hz), lower F6 (976.7 to 1090.0 Hz vs. 1160.0 to 1403.3 Hz), lower F7 (1035.0 to 1106.7 Hz vs. 1220.0 to 1516.7 Hz), lower F8 (868.3 to 973.3 Hz vs. 1020.0 to 1123.3 Hz).

Otus bikegila sp. nov. differs from O. scops in seven morphological and 11 bioacoustic characters: higher Biwid (9.0 to 11.8 mm vs. 5.5 to 7.8 mm), larger Binares (11.3 to 12.6 mm vs. 9.0 to 11.5 mm), longer Tarlen (30.5 to 35.1 mm vs. 22.0 to 28.0 mm), shorter Wilen (145 to 151 mm vs. 147 to 165 mm), longer SP10 (37 to 40 mm vs. 12 to 24 mm), longer SP9 (13 to 18 mm vs. 0 to 7 mm), shorter SP4 (6 to 9.5 mm vs. 10 to 29 mm), lower F1 (781.7 to 961.7 Hz vs. 1335.0 to 1695.0 Hz), lower F2 (933.3 to 1020.0 Hz vs. 1152.5 to 1275.0 Hz), lower F3 (980.0 to 1090.0 Hz vs. 1155.0 to 1260.0 Hz), lower F4 (950.0 to 1050.0 Hz vs. 1200.0 to 1285.0 Hz), lower F5 (931.7 to 1020.0 Hz vs. 1193.3 to 1318.3 Hz), lower F6 (976.7 to 1090.0 Hz vs. 1210.0 to 1326.7 Hz), lower F7 (1035.0 to 1106.7 Hz vs. 1336.3 to 1628.3 Hz), lower F8 (868.3 to 973.3 Hz vs. 1140.0 to 1253.3 Hz), shorter DT4 (0.992 to 1.121 s vs. 2.423 to 2.789 s), higher DF1 (6.7 to 178.3 Hz vs. -420.0 to -182.5 Hz), lower DFT1 (-581.5 to 45.2 Hz/s vs. 181.5 to 662.3 Hz/s); and in the following molecular characters: KIAA (T vs. C in site 347, A vs. G in site 632); TTN (T vs. C in site 535, G vs. A in site 536, G vs. T in site 634); TGFB2 (G vs. A in site 33, G vs. T in site 47, A vs. G in site 178, T vs. C in site 285).

Otus bikegila sp. nov. differs from O. cyprius in four bioacoustics characters (morphology and nuclear markers not analysed): presence of a monosyllabic primary song ( O. cyprius has a distinctive di-syllabic primary song), lower F1 (781.7 to 961.7 Hz vs. 1236.7 to 1400.0 Hz [long note] and 1058.9 to 1223.3 Hz [short note]), shorter DT4 (0.992 to 1.121 s vs. 3.035 to 3.643 s [long note] and 3.116 to 3.714 [short note]), and having a higher DF1 (6.7 to 178.3 Hz vs. -283.3 to -165.0 Hz [long note] and -113.3 to -58.1 [short note]).

Otus bikegila sp. nov. differs from O. brucei in 11 bioacoustic characters (morphology not analysed): higher F1 (781.7 to 961.7 Hz vs. 285.0 to 388.3 Hz), higher F2 (933.3 to 1020.0 Hz vs. 891.7 to 946.7 Hz), higher F3 (980.0 to 1090.0 Hz vs. 356.7 to 530.0 Hz), higher F4 (950.0 to 1050.0 Hz vs. 356.7 to 493.3 Hz), higher F5 (931.7 to 1020.0 Hz vs. 335.0 to 450.0 Hz), higher F6 (976.7 to 1090.0 Hz vs. 370.0 to 510.0 Hz), higher F7 (1035.0 to 1106.7 Hz vs. 370.0 to 530.0 Hz), higher F8 (868.3 to 973.3 Hz vs. 270.0 to 373.3 Hz), longer DT1 (0.231 to 0.248 s vs. 0.090 to 0.133 s), longer DT2 (0.078 to 0.112 s vs. 0.032 to 0.053 s), higher DFT2 (-250.3 to 21.7 Hz/s vs. -1653.0 to -1387.3 Hz/s); and in the following molecular characters: MYO2 (T vs. C in site 22; C vs. T in site 118; C vs. T in site 129).

Otus bikegila sp. nov. differs from O. ireneae in one bioacoustic character (morpho-logy and nuclear markers not analysed): longer DT4 (0.992 to 1.121 s vs. 0.409 to 0.447 s).

Description of the holotype.

Morphological measurements available in Table 1 . The topographic terms of the scops-owl body are detailed in the Suppl. material 3.

General colouration: Back, Burnt Amber 48 with Robin Rufous 29 shades; front, Pale Buff 1 feathers with Cinnamon 21 and Dusky Brown 285 markings (forming stripes defined by Dusky Brown 285 lines) with Robin Rufous 29 shades.

Head: Chin feathers Pale Buff 1 with Sayal Brown 41 shading along shaft, ending with a bristle-like barb Sepia 286. Throat feathers Pale Buff 1 with Pale Pinkish Buff 3 and Sepia 286 dots and markings sometimes forming bands; Pale Buff 1 shaft proximally becoming Pale Pinkish Buff 3 and Sepia 286 distally. Feathers of forehead Sepia 286 and few Pale Buff 1 shading. Tip of the head triangle Prout’s Brown 47. Triangle outside facial disk with an overall appearance Prout’s Brown 47, triangle with feather with Sepia 286 middle stripe along shaft, Prout’s Brown 47 and Sepia 286 in their internal portion and Sepia 286 and Pale Buff 1 in the outer portion but always ending with Prout’s Brown 47 or Robin Rufous 29 in the distal portion. Triangle delineated by Pale Buff 1/Smoke Grey 266 stripes (the eyebrows). Eyebrows Pale Buff 1/Smoke Grey 266 down to the bill: Pale Buff 1 feathers ending with a thin Cinnamon 21 line followed by a broader Jet Black 300 band; Pale Buff 1 feathers with middle Sepia 286 stripe along shaft and densely vermiculated with Sepia 286 and Cinnamon 21 shades; eyebrows feathers in distal portion are Pale Buff 1 densely vermiculated with Sepia 286 and Cinnamon 21 shades, ending in Prout’s Brown 47. Crown feathers Prout’s Brown 47 with Sepia 286 middle stripe along shaft, Pale Buff 1 in proximal section and Prout’s Brown 47 with Sepia 286 vermiculation along mid and distal portion. Ear tuft not visible in the mounted specimen, but with feathers Pale buff 1 in proximal section becoming Cinnamon 21 with densely Sepia 286 vermiculation and ending with Prout’s Brown 47; ear feathers pull up some of the eyebrow feather with Sepia 286 and Cinnamon 21 dense vermiculation. Nape feathers Pale Pinkish Buff 3 with well-defined Sepia 286 irregular stripes, ending with middle Sepia 286 stripe along shaft and Burnt Amber 48. Neck feathers with longer underfeathers (then in nape) with middle Sepia 286 stripe along shaft with Pale Pinkish Buff 3, Pale Buff 1, Pale Pinkish Buff 3 and becoming Pale Buff 1 and Burnt Amber 48 all with Sepia 286 irregular markings. Overall appearance of rictal bristles: Jet Black 300 patches with Cinnamon 21 and Pale Buff 1 shades next to the bill (following with Pale Buff 1/Smoke Grey 266 eyebrows); bristles with terminal Jet Black 300 colour; bristles closer to the bill Pale Buff 1 in proximal position, changing into Cinnamon 21 and ending in Jet Black 300 or Pale Buff 1 in the proximal section and Jet Black 300 in distal section; bristles closer to the eye Jet Black 300 in proximal position, changing into Cinnamon 21 and ending in Jet Black 300 or only Jet Black 300 (the shortest one). Rim with two narrow Raw Umber 23 bands, one on each side, not extending to the centre; Pale Buff 1 feathers with Sepia 286 irregular markings, becoming Cinnamon 21 (with no Sepia 286 markings), ending with Raw Umber 23. Facial disk feathers Pale Buff 1 with multiple bands of Sepia 286 (generally 3), the terminal Sepia 286 bands is preceded by a thin Robin Rufous 29 band; feather ending with 2 to 5 bristle-like barbs.

Upperparts: Overall colour of mantle (i.e., upper back) and rump: Burnt Amber 48 with Robin Rufous 29 shades. Feathers Sayal Brown 41 with middle Sepia 286 line along shaft, and with irregular Sepia 286 markings in the proximal section. Feathers turning Cinnamon-Rufous 31 with Sepia 286 markings in the distal portion of the feather. Mantle is delimited distally (neck) by a Cinnamon-Rufous 31 band and late-rally by a series of 8 feathers that are lighter in colour (Cinnamon-Rufous 31): outer vane Light Buff 2 with Cinnamon-Rufous 31 shades and with a Sepia 286 curve line that defines a Raw Sienna 32 colour close to shaft, one or more Sepia 286 spots on distal outer vane; outer vane ending distally with Raw Sienna 32 with Sepia 286 mar-kings; inner vane is Raw Sienna 32 with Sepia 286 irregular markings. These feathers appear to make a line that delineates the outside of the mantle. Similarly, the feathers of the mantle at the base of the neck form a lighter Cinnamon Rufous 31 line that follows the external side of the folded wings, making a triangle. Scapulars as upperparts. Proximal shaft Pale Buff 1, Vandyke Brown 282 in distal portion; Vandyke Brown 282 middle stripe along shaft. Outer vane is Cinnamon 21 with Sepia 279 markings and inner vane is Sepia 279 with Cinnamon 21 markings.

Underparts: Breast overall Pale Buff 1 with Sepia 286 irregular markings and Robin Rufous 29 shading. Breast feathers Pale Pinkish Buff 3 with Sepia 286 dots and markings proximally and Pale Pinkish Buff 3 shaft, distally Sepia 286 with Pale Pinkish Buff 3 dots and markings forming irregular bands, middle Sepia 286 stripes along shaft. Belly overall similar to breast but with colours more defined and with Light Buff 2 shadings. Belly feathers Pale Pinkish Buff 3 in proximal section followed by a Sepia 286 V stripe. This is followed by a Pale Buff 1 broad band delimitated distally with a thin Pale Pinkish Buff 3 line followed by a Sepia 286 line. Distally, these feathers are Pale Buff 1 with irregular spots Sepia 286 and Pale Pinkish Buff 3. Some feathers on the belly and the vent have a marked middle and broad Sepia 286 line along shaft. Vent is similar to breast and belly but with feathers Cinnamon 21 in proximal section followed by a Sepia 286 stripe. This is followed by a Pale Buff 1 broad band delimitated distally with a thin Cinnamon 21 followed by a Sepia 286 line. The feather then becomes Pale Buff 1 with a Cinnamon 21 thin band followed by a Sepia 286 line, ending with a Pale Buff 1 colouration with Sepia 286 irregular dots and markings. Flank feathers Pale Buff 1 with Cinnamon 21 shading followed by a broad Cinnamon 21 V stripe followed by a Sepia 286 line, ending with a broad Pale Buff 1 section with Sepia 286 markings only in the very distal portion. Undertail coverts are similar to flanks but with more defined bands. Feathers are Pale Buff 1 followed by a broad Cinnamon 21 band defined distally by a thinner warm Sepia 40 line. This colouration is repeated twice. Feathers end with a broad Pale Buff 1 band followed by a Cinnamon 21 band with irregular Warn Sepia 40 markings. Tarsus covered with feathers to base of toes. Feathers overall similar to flank but with less Pale Buff 1 and more Cinnamon 21 shading and one or two Sepia 286 dots in distal section. Tarsus fea-thers have a larger proportion of Pale Buff 1 close to toes. Tarsus feathers are Pale Buff 1 proximally, followed by Cinnamon 21 shading and Sepia 286 markings distally (approximately 1/4 of the feather distally), no middle stripe along shaft. Toes feathers are Pale Buff 1 with Cinnamon 21 shadings and Sepia 286 markings only in the distal section.

Wing: Overall Prout’s Brown 47 with Dark Greyish Brown 284 leopard blotches. Primaries shaft Vandyke Brown 282. Outer vane of primaries with six or seven ‘leopard’ Dark Greyish Brown 284 spots in Cinnamon 21 background becoming Pale Buff 1 in some instances. Spots interior with a gradient of Cinnamon 21 to Dark Greyish Brown 284 with lighter spots on outer primaries. Spots circumference with Dark Greyish Brown 284 to Jet Black 300. 'Leopard spots’ start faint (P1-P2-P3) and become stronger moving outwards. Inner vane of primaries with Dark Greyish Brown 284 with Cinnamon 21 shadings towards the distal section of the feather. Exterior edge makes a Pale Buff 1 line. Under-primaries have a Pale Buff 1 shaft proximally becoming Cinnamon 21 towards the distal portion. Outer vane of under-primaries is proximally Hair Brown 277 with Pale Pinkish Buff 3 irregular triangles, becoming Cinnamon 21 in distal section with Sepia 279 lines delimiting the leopard spots that are fading towards the distal portion of the feather. Inner vane of under-primaries is Hair Brown 277 with Light Buff 2 markings in proximal section and Cinnamon 21 markings in distal section. Secondaries shaft Vandyke Brown 282. Outer vane of secondaries is similar but much less marked pattern than primaries: spots on outer vanes less marked, fading into the background towards S10. Inner vane of seconda-ries with Sepia 279 with Cinnamon 21 shadings and markings especially towards the distal section of the feather. Under-secondaries have a Pale Buff 1 shaft proximally becoming Cinnamon 21 and later Sepia 279 towards the distal portion. Outer vane of under-secondaries with Hair Brown 277 with Cinnamon 21 markings. Inner vane of under-secondaries with Hair Brown 277 with six to seven Light Buff 2 triangles only on the outer part of the inner vane, which become irregular markings (Cinnamon 21 in colour) towards the distal portion of the feather. Tertiaries shaft like primaries (Vandyke Brown 282). Outer and inner vane of tertiaries similar in colour and similar to the outer vane of the secondaries. Under-tertiaries have Pale Buff 1 shaft proximally becoming Cinnamon 21 and later Sepia 279 towards the distal portion. Outer and inner vanes of under-tertiaries are similar: Cinnamon 21 with irregular Sepia 279 lines in the proximal portion, becoming irregular dots towards the distal section; terminal 1/5 with a Sepia 279 middle stripe along shaft. Primary coverts with Vandyke Brown 282 shafts. Outer vane of primary coverts with Sepia 279 with Cinnamon 21 markings becoming more packed towards the distal portion of the feather. Inner vane of primary coverts is similar to outer but with less packed Cinnamon 21 markings. Secondary coverts are overall Sepia 279 with Cinnamon 21 markings. Shaft is Vandyke Brown 282. Outer vane of secondary coverts with a Pale Buff 1 blotch delimited proximally by a Sepia 279 thin and sharp line. This blotch can have in its inner parts a Cinnamon 21 blotch delimited by a Sepia 279 thin and sharp line. Additional Sepia 279 lines distributed heterogeneously can be found on the outer vane. Inner vane of secondary coverts Sepia 279 with Light Buff 2 markings in proximal section and Cinnamon 21 markings in the distal portion of the feather. Lesser coverts with shafts Pale Buff 1 proximally and Vandyke Brown 282 in distal portion. Vandyke Brown 282 middle stripe along shaft. Outer vane of lesser co-verts Cinnamon 21 with Sepia 279 markings and Pale Pinkish Buff 3 markings delimited irregularly by Sepia 279 dashed lines. Inner vane of lesser coverts Sepia 279 with Cinnamon 21 markings. Coverts in the under-wings with Pale Buff 1 shaft. Outer vane on the coverts from the under-wings is Pale Buff 1 and Light Buff 2 with one Sepia 279 leopard spot and some additional (but rare) Sepia 279 markings. Inner vane of the coverts from the under-wings Pale Buff 1 and Light Buff 2 with Light Neutral Grey 297 colouration that become Sepia 279 distally. Alula shaft is Vandyke Brown 282. Outer vane of alula with five Verona Brown 37 ‘leopard’ spots delimited by Sepia 279 lines which is sharper in distal portion. Leopard spots separated by Pale Pinkish Buff 3 with Cinnamon 21 shadings. Inner vane of alula Sepia 279 with four Light Buff 2 partial bands.

Tail: Verona Brown 37 with Sepia 286 markings that fades towards the distal portion of the feather. Shaft Sepia 286. Outer feathers of the tail have an outer vane Verona Brown 37 with broad Sepia 286 bands, and an inner vane with broad poorly defined Sepia 286 bands intercalated by Light Buff 2, Pale Pinkish Buff 3 and more distally Verona Brown 37 bands.

Bill: Dusky Brown 285 and lower bill Light Buff 2.

Iris: Yellow.

Vocalisations: Call recordings collected at the moment of specimen collection included the call of the holotype and a second individual (XC audios: XC619445, XC619447): one emitted the main call type (the single repetitive note used in the bioacoustic analyses), and the other the cat-like call. We believe that the holotype individual was the one giving the main call, but this was uncertain. Thus, it is not possible to provide bioacoustics parameters specific to the holotype.

Variation: Morphometric variation in O. bikegila sp. nov. is based on the analysis of three additional individuals, of which one is a male (Table 1 ; Fig. 2 ). The male (P9-038) had shorter tarsus and wing length than the female holotype and the other two females. This result is consistent with the reversed sexual dimorphism in size described for all species of scops-owls ( Marks et al. 1999; König et al. 2008). Two colour morphs (rufous and grey-brown) have been documented in the field (Figs 2 , 9 ). Molecular sexing of the four captured individuals has shown that colour morph is not associated with sex. Examples of the grey-brown morph include the holotype (Figs 2A , 8 ), individuals P9-037 and P9-038 (Fig. 2B ), and individuals photographed in the field (Fig. 2D, E ); examples of the rufous morph include the first photographed individual of this species (Fig. 2C ) and individual P8-001 (Fig. 2F ). Plumage pattern and colour of the latter is similar to the holotype, although in the rufous morph the eyebrows are less marked, the underparts are more similar in colour to the upperparts and have more prominent sepia marks and stripes along the feather shafts. In the field, we observed no differences in the rate of occurrence of the two morphs.

Vocalisations were recorded at the type locality by MM in 2002, 2007, 2011, 2018 and 2019 and at Boca do Inferno in 2019, and by PV at the type locality in 2016. The call of O. bikegila was described in Melo and Dallimer (2009). Among vocalisations of Otus species, the primary call of O. bikegila sp. nov. is unique in consisting in a short, undulated note emitted at a fast repetition rate, reminiscent of insect calls, of ca. one note per second (Tables 2 , 3 ; Fig. 4 ; Suppl. material 4: Fig. S2A). Vocalisations were often performed in duet (Suppl. material 4: Fig. S2B), with intercalated or overlapping notes. Otus bikegila sp. nov. is able to produce a cat-like “kee-a-u” note, which is emitted both in duets (Suppl. material 4: Fig. S2D) and by single birds (Suppl. material 4: Fig. S2C). We confirmed in the field that the same individual can produce both calls. Bioacoustic parameters (mean ± standard deviation) of the primary and of the cat-like notes are available in Tables 2 , 3 .

Etymology.

The species name is a patronym honouring Ceciliano do Bom Jesus, known as ‘Bikegila’ (Suppl. material 5). The species epithet name is intentionally defined as an invariable noun in apposition (not a noun in the genitive case) for better pronunciation; no confusion with the species authority is possible because the noun is an oral nickname.

Bikegila, a native of Príncipe Island, began the ‘Príncipe Scops-Owl saga’ in 1998, when he shared with MM reports of two sightings of birds that looked like owls in parrot nests. Since then, Bikegila took part in every field effort that led to the bird’s discovery for science; he also led the capture of all sampled individuals, including the holotype, which required ingenious ways to erect canopy nets. For almost 25 years, Bikegila has put all his resources, including bottomless fieldwork skills and a vast knowledge of Príncipe, towards the successful completion of innumerable research projects in a terrain that the collector José Correia considered to be the " bad among the bad or the worse among the worse " [sic] (Diary, 2 September 1928, Archives AMNH, New York). Besides his skills, Bikegila’s " cheerful temperament, possibly the first requirement for an undertaking in inhospitable regions " ( von Humboldt 1841), coupled with an unbeatable gift for story-telling and an underlying quiet wisdom, contributes as much to making the expeditions he leads memorable and successful. A former parrot harvester, Bikegila became a warden of Prín-cipe Obô Natural Park soon after its creation; he is now a much sought-after nature guide.

We believe that most field researchers are grateful to the ‘Bikegilas’ with whom they are/were honoured to work with. As such, the name is also in recognition of all the people, around the world, who through their deep relationship with and knowledge of the regions they inhabit, play key roles in the description of new species and of new sites to science.

Common name.

We propose the English common name Principe Scops-Owl, the name for São Tomé and Príncipe as Kitóli-do-príncipe, and the name for the Portuguese list of the birds of the world as Mocho-do-príncipe. All common names refer to Príncipe Island, from where it is endemic.

Distribution and natural history.

All records from O. bikegila sp. nov. come from old-growth native lowland rainforest with mid-height (14-20 m) trees (Fig. 10 ), with the species apparently preferring lower elevations ( Melo and Dallimer 2009; Freitas et al. 2022). Its area of occurrence is fully within the limits of Príncipe Obô Natural Park. Detailed surveys have been carried out to determine the area of occupancy of this species, to estimate its population size, ecological requirements, and to propose an IUCN Red List category ( Freitas et al. 2022).

The holotype (Figs 2A , 8 ; female MHNC-UP-AVE7000), collected on 29 May 2017, was undergoing a well-advanced moult, a process that takes place after the breeding season. The female captured close to Ribeira Porco, in January 2019 (P8-001) had a fully developed brood patch (Fig. 2F ), whereas the female captured at Boca do Inferno on the same month (Fig. 2B , left) was growing back the belly feathers, suggesting that she had a recent brood patch. This indicates that breeding takes place in December-January, as with most bird species of the islands of São Tomé and Príncipe ( Jones and Tye 2006; Madeira 2018).

Otus bikegila sp. nov. starts calling at dusk and continues throughout the night. Contrarily to the Sao Tome Scops-Owl O. hartlaubi that regularly vocalises during the day, O. bikegila sp. nov. seems to require darkness to sing, although on a single occasion one individual was heard during the day ( Melo and Dallimer 2009). Response to the playback of its call was fast and intense at all times of the year we were able to test it, with birds of either sex approaching the speaker. This indicates that O. bikegila sp. nov. is territorial all-year round as it is known from most sedentary cavity-nesting owls ( Marks et al. 1999; König et al. 2008). During the day it may roost outside of tree cavities, as suggested when we accidentally flushed one bird when taking habitat measurements. In this situation the bird raised its ear tufts, which are otherwise seldom observed (Fig. 2D ).

Figures

Figure 1. Altitudinal A and land use maps B of Principe Island, with the limits of the Principe Obo Natural Park (PONP) and its buffer zone, and the two localities where the four individuals of the candidate species of Otus from Principe were captured; inset: location of Principe in Africa.

Figure 2. The candidate species of Otus from Principe A female specimen MHNC-UP-AVE 7000, showing colouration in life (available also in the Macaulay library (ML): ML 470442301; grey-brown morph) B female (left, sample P 9 - 037) and male (right, sample P 9 - 038) grey-brown morphs captured at Boca do Inferno on January 28, 2019 (ML 470438621) C rufous morph individual photographed at Ribeira Porco area on July 04, 2016 D daytime sighting of a grey-brown morph individual between Rio Sao Tome and Ribeira Porco on January 19, 2019 (ML 470443361, only the rufous upperparts are clearly seen) E grey-brown morph individual photographed in the Ribeira Porco area on January 21, 2019 F fully developed brood patch of a female rufous morph (sample P 8 - 001) captured in the Ribeira Porco area on January 20, 2019 (ML 470440211). ML - Macaulay Library. Photographs: A - HP B, D, F - MM and BF C - PV E - Paul van Giersbergen.

Figure 4. Oscillograms and spectrograms of 2 - s sections of the song of O. bikegila sp. nov. (XC 619448), O. hartlaubi (XC 673669), O. senegalensis senegalensis (XC 45502), O. senegalensis feae (XC 340505), O. pembaensis (XC 253581), O. pamelae (XC 371431), O. scops (XC 383983), O. cyprius (XC 256102), O. brucei (XC 158086), and O. ireneae (XC 147630). Each section refers to an individual owl. For more information about the recordings used see Suppl. material 7. Codes from Xeno-canto. org database.

Figure 8. Otus bikegila sp. nov., female holotype (MHNC-UP-AVE 7000). Views A dorsal B ventral C lateral D left wing top and E left wing under. Millimetric paper on the background and colour reference plate (Colorchecker, X-Rite Inc.) for size and colour assessment.

Figure 9. Principe Scops-Owl Otus bikegila sp. nov. from Principe Island, Africa. Left: Adult rufous morph in the typical posture. Right: Adult grey-brown morph in a stress posture, when it raises the ear tufts to increase the efficiency of camouflage. Original artwork by MNC.

Figure 10. A aerial view of the south of Principe Island home of Otus bikegila sp. nov., and B habitat of the type locality at ca. 150 m a. s. l. Photographs: A Alexandre Vaz B MM.