Stiphrornis pyrrholaemus, Schmidt, Brian K., Foster, Jeffrey T., Angehr, George R., Durrant, Kate L. & Fleischer, Rob- Ert C., 2008

Schmidt, Brian K., Foster, Jeffrey T., Angehr, George R., Durrant, Kate L. & Fleischer, Rob- Ert C., 2008, A new species of African Forest Robin from Gabon (Passeriformes: Muscicapidae: Stiphrornis), Zootaxa 1850, pp. 27-42 : 29-32

Stiphrornis pyrrholaemus , sp. nov. (Schmidt & Angehr)

Olive-backed Forest Robin (English)

Rougegorge de forêt à dos olive (French)

Holotype — USNM 631622; adult male (skull 100% pneumatized and no bursa), from northwest corner of N’dogo Lagoon within Moukalaba–Doudou National Park, Ogooue Maritime Province, Gabon (2°25’14”S, 10°14’04”E); elevation <200m; collected on 14 Apr 2003 by Brian K. Schmidt (BKS 6309, tissue B15037) and prepared by him as a study skin, tissue preserved in Seutin buffer solution ( Seutin, et al. 1991), and trunk preserved in 3% formalin. Mitochondrial and nuclear DNA sequences were deposited in GenBank (accession no. EU423168 ).

Diagnosis —Typical of other members of the genus Stiphrornis with its fine bill and weak rictal bristles, white loral spot, long legs, short tail, and rich orange on the throat and chest ( Irwin & Clancey, 1974). Distinguished from S. gabonensis , S. xanthogaster , and S. erythrothorax by its yellow belly, and differs from S. sanghensis (only other member of the genus with prominent yellow belly) by its olive-green back, rump, and upper tail coverts, and its darker orange throat ( Table 1 ).

Description of holotype —Capitalized color designations (corresponding number in parentheses) from Smithe (1975). Forehead and crown Blackish Neutral Gray (color 82). Nape dark gray with slight Olive- Green (aux. 48) wash increasing dorsally. Back and rump Olive-Green (aux. 48). Rectrices Fuscous (color 21) fringed slightly browner than rump and same color as the upper tail coverts. Remiges Brownish-Olive (color 29) narrowly fringed with Olive-Green (aux. 48). Wing coverts gray with olive fringing. Wing lining whitish and axillaries creamy yellow. Malar and eye ring black. Loral spot white. Auricular black blending to Blackish Neutral Gray (color 82) posteriorly. Chin and throat Spectrum Orange (color 17). Upper breast dark orangish ochre with feather fringes on sides of breast Medium Neutral Gray (color 84). Lower breast and belly creamy yellow with under tail coverts slightly darker. Flanks and sides Medium Neutral Gray (color 84). Soft parts in life: iris dark brown, bill black, legs and feet pink-gray ( Figs. 2 , 3 ).

Measurements of holotype —Wing chord 68.7 mm; tail 41.1 mm; culmen from base of feathers 14.1 mm; bill width at anterior edge of nares 3.6 mm; bill depth at anterior edge of nares 4.05 mm; tarsus 24.7 mm; mass 20.5 g; skull 100% pneumatized; left testis 2 x 1.5 mm, gray in color.

Description of allotype —USNM 631537; adult female (skull 100% pneumatized, no bursa) from northwest corner of N’dogo Lagoon within Moukalaba–Doudou National Park, Ogooue Maritime Province, Gabon (2°25’14”S, 10°14’04”E); elevation <200m; collected on 31 Mar 2003 by Brian K. Schmidt (BKS 6224, tissue B16312) and prepared by him as a study skin, tissue preserved in Seutin buffer solution, and trunk preserved in 3% formalin. Mitochondrial and nuclear DNA sequences were deposited in GenBank (accession no. EU423171 ). Forehead and crown gray with slight Olive-Green (aux. 48) wash. Back and rump Olive-Green (aux. 48). Rectrices Fuscous (color 21) fringed slightly browner than rump and same color as the upper tail coverts. Remiges slightly lighter than Brownish-Olive (color 29) narrowly fringed with Olive-Green (aux. 48) in the holotype. Wing coverts gray with olive fringing. Wing lining whitish and axillaries creamy yellow. Malar and eye ring Medium Neutral gray (color 84). Loral spot white. Auricular black blending to Blackish Neutral Gray (color 82) posteriorly. Chin and throat Orange Yellow (color 18). Upper breast light orangish ochre with feather fringes on sides of breast Medium Neutral Gray (color 84). Lower breast and belly cream colored (not as yellow as holotype) with under tail coverts slightly darker. Flanks and sides Medium Neutral Gray (color 84). Soft parts in life: iris dark brown, bill black, legs and feet pink-gray ( Figs. 2 , 3 ).

Measurements of allotype —Wing chord 60.4 mm; tail 35.3 mm; culmen from base of feathers 14.1 mm; bill width at anterior edge of nares 3.8 mm; bill depth at anterior edge of nares 4.2 mm; tarsus 23.1 mm; mass 17.5 g; skull 100% pneumatized; ovary 6 x 3 mm, granular.

USNM Sex Weight Wing Tail Culmen Bill Depth Bill Width Tarsus 631537 F 17.5 60.4 35.3 14.1 4.2 3.8 23.1 616804 M 17.0 61.9 28.2 14.4 3.7 3.8 24.6 631495 M 19.0 - - - - - - 631496 F 19.0 - - - - - - 631501 M 18.0 67.6 39.5 13.0 3.7 3.7 25.1 631584 F 17.0 - - - - - - 631486 M 19.0 - - - - - - 631511 M 18.5 62.3 41.5 13.3 3.6 3.6 24.8 631520 F 16.0 - - - - - - 631524 F 18.0 64.2 32.4 12.6 3.9 3.6 24.1 631622* M 20.5 68.7 41.1 14.4 4.05 3.6 24.7 616712 F 18.5 61.9 28.2 13.4 3.7 3.6 24.5

* type specimen.

Paratypes —There are a total of ten additional specimens from the type series. One skin specimen has been returned to Gabon for their collections (USNM 631501) and the remaining nine are deposited at USNM with associated tissue samples (B numbers) preserved in Seutin buffer solution. Two specimens from Rabi Oil Field: female, fluid preserved, USNM 616712, B10005; and male, fluid preserved, USNM 616804. Eight specimens from Moukalaba–Doudou National Park: male, skeleton, USNM 631486, B16281 ( Fig. 3 ); male, skeleton USNM 631495, B16285; female, skeleton, USNM 631496, B16286; male, skin and fluid preserved trunk, USNM 631501, B16291 (housed at the Smithsonian’s biodiversity lab at Vembo near Gamba, Gabon, until adequate facilities are available for permanent storage in Gabon); male, fluid preserved, USNM 631511; female, skeleton, USNM 631520, B16300; female, skin and fluid preserved trunk, USNM 631524, B16304; and female, skeleton, USNM 631584, B16347.

Measurements and color of type series —Morphological measurements of the type series ( Table 2) were taken with digital calipers and rounded to the nearest 0.1 mm: wing chord; tail (from point of insertion to tip of central retrix); culmen (from anterior extension of feathers); bill depth at anterior edge of nares; bill width at anterior edge of nares; and tarsus. Weights to the nearest 0.1 gram were obtained immediately after capture by using a Pesola spring scale to weigh the bird in the cloth bag and then subtracting bag weight.

Color measurements from the type series were obtained using a calibrated colorimeter (CR-221 Chroma Meter, Minolta Corporation) following procedures described by Graves (1999). The procedure was repeated five times for each area of plumage. Each datum summarized in Table 3 represents five independent measurements. Colorimetric characters were described in terms of opponent-color coordinates (L, a, b) ( Hunter 1987). This system uses three coordinates to express colors. The L coordinate, ranging from 0 to 100, describes the “lightness” of color; low values are dark and high values are light. The a coordinate describes the “redness” and “greenness”; reds have positive value and greens negative value. The third coordinate b describes the “yellowness” and “blueness”; yellows have positive value and blues negative value. These measurements confirm visual differences between the males and females: males have darker orange throat, darker head, and yellower belly. Both sexes share similar back coloration.

Other specimens —Only one other S. pyrrholaemus specimen has been identified outside the type series. A juvenile unsexed skin at the Muséum d’Histoire Naturelle de Paris ( NMHN 1954-56) was collected by P. Rougeot on 11 Nov 1953 in Tchibanga, Gabon. Identification was confirmed using ancient DNA techniques (see phylogenetic relationships section below). Berlioz (1954) noted that the upperparts were a deep olive brown (brun olivâtre foncé) and the entire underparts strongly tinted yellow (fortement teinté de jaune), with an intense but poorly defined area of russet (roussâtre) on the breast. The yellow on the specimen has obviously faded since Berlioz’s description as the underparts are currently white with a hint of yellow and the breast a dull russet. The throat is slightly more yellow than the underparts and the feathers are sparsely tipped gray which is usually a juvenile trait. Likewise, the olive gray wing coverts and tertials have light brown tips giving a spotted appearance which is also a juvenile trait in this genus. The forehead, crown, and nape are lighter gray than in adults and lacking the olive wash. The white loral spot is not as prominent as in adult birds. Berlioz doubtfully assigned it to S. xanthogaster because of its strongly yellowish underparts, but believed that this coloration could have been a juvenile trait as in some other thrushes. He also remarked that if this specimen were actually xanthogaster , it would be “paradoxical” to find the subspecies with yellow underparts known from southeast Cameroon, instead of that with a white abdomen known from western Cameroon and Gabon. Berlioz’s (1954) bewilderment is understandable now that we know this specimen is actually a member of the new species.

Etymology —The brilliant orange ‘flame’ colored throat of this species outshines the others in the genus. The pyrrho - prefix signifies ‘orange colored’ and the – laemus suffix refers to ‘the throat’. The combined Greek name is meant to describe: A stout/sturdy bird ( Stiphrornis ) that bears a flame colored throat ( pyrrholaemus ). Combined with the English common name of Olive-backed Forest Robin which highlights the distinctive olive back and rump, the bird is aptly described by its names.

Distribution —The full distributional range of the new species is not known. In addition to our specimens and observations from the Rabi Oil Field (1°52’S, 9°53’E), along the road to Toucan (1°51’S, 9°51’E) immediately north of Rabi, and Moukalaba–Doudou National Park, and the 1953 specimen from Tchibanga (2° 51’S, 11° 01’E), we found Stiphrornis at two other localities in the Gamba Complex: near Gamba (2°45’S, 10°01’E) and near our base camp in Loango National Park (2°20’S, 9°35’E) ( Fig. 1 ; see Angehr et al. 2005, 2006 for descriptions of these localities). We obtained tape recordings at the Gamba and Loango sites but did not capture, photograph, or observe individuals closely enough there to be certain of their species identity. Based on calls, we found Stiphrornis to be common at Gamba and our camp at Moukalaba–Doudou, and uncommon in the Rabi–Toucan area and our camp in Loango National Park ( Angehr, et al. 2005).

of type series specimens. L (Lightness), a (Red[+]/Green[-]), b (Yellow [+]/Blue[-])

* type specimen.

There are few published specimen records of Stiphrornis for Gabon ( Fig. 1 ). As noted by Beresford and Cracraft (1999), records of S. gabonensis are limited to north of the Ogooué River, including Kango ( Malbrant & Maclatchy 1949), Cap Esterias ( Rand, et al. 1959) and O'Veng ( Berlioz 1955), all in the vicinity of Libreville, and near Oyem in Woleu–N’Tem province ( Rougeot 1951), the last apparently the farthest inland. Records of S. xanthogaster from Gabon are limited to Bélinga and Makokou in the northeast ( Beresford & Cracraft 1999; Brosset & Erard 1986, specimens in Muséum d'Histoire Naturelle de Paris). The only record of Stiphrornis south of Gamba and Tchibanga is from the Kouilou area of the Mayombe region of Republic of the Congo ( Dowsett-Lemaire & Dowsett 1991). Although Dowsett-Lemaire and Dowsett found Stiphrornis to be common, they did not note subspecies (as the known taxa were then treated) or describe the plumage.

Specimens from central Gabon will be of great interest in elucidating the relationships between the different forms. It is of interest to note that Christy and Clarke’s (1991) description and illustrations of birds from the Lopé National Park suggest either that two different forms are present there, or that the population is intermediate and variable. They describe the species as having dark slate-gray upperparts, orange-yellow to bright orange underparts and a pure white belly, with some individuals having a brilliant orange throat and a citronyellow breast. Their illustration shows birds with entirely gray upperparts, yellow-orange throat and upper breast, bright yellow lower breast, and white belly. Likewise, a photograph of a Stiphrornis by Don Roberson in 1996 (pers. comm.) from Lopé with orange throat and yellow belly might also suggest that the new species occurs north to Lopé, but the bird in the photo cannot be identified conclusively.

Figures

FIGURE 1. Stiphrornis records in Gabon and southern Republic of the Congo. Filled circles = S. gabonensis, filled squares = S. xanthogaster, filled triangles = S. pyrrholaemus, crosses = Stiphrornis recorded but species identity unknown or uncertain.

FIGURE 2. Stiphrornis pyrrholaemus watercolor by John Anderton. Male above, female below.

FIGURE 3. Above: handheld photographs of male Stiphrornis pyrrholaemus from Moukalaba – Doudou National Park (USNM 631486). Bottom: Holotype specimen USNM 631622 (top) and allotype USNM 631537 (bottom). Photos by Brian K. Schmidt.

Tables

TABLE 1. Summary of plumage variation in Stiphrornis (modified from Beresford & Cracraft 1999).

Plumage/body part	pyrrholaemus	sanghensis	xanthogaster	gabonensis	erythrothorax
Forehead, fore- crown, and crown	Dark gray to black	Gray to dark gray with olive wash	Gray to dark gray with olive wash	Darker gray with faint olive wash	Gray with green wash
Nape, mantle, and back	Olive green	Gray with olive wash	Gray with olive wash	Slaty gray, only faintly tinged olive	Gray with green wash
Chin, throat, and breast	Bright orange	Bright yellow orange	Tawny; varies to pale beige at chin and throat	Russet	Russet
Upper and lower belly	Cream Yellow	Yellow	Cream	White	White
Upper wing coverts	Gray with olive fringes	Dark brown	Dark brown	Dark brown to slaty gray	Dark brown edges olive
Rump, upper tail coverts and dorsal surface of rectrices	Olive Green	Gray washed yel- low-green	Gray with olive wash generally brighter than on back	Gray with olive wash generally brighter than on back	Gray with green wash, not distinct from back
Lesser underwing coverts	Gray tipped white	Gray tipped yel- low	Gray tipped cream	Gray tipped white	Gray tipped white
Flank and tibiotar- sus	Gray	Light gray tipped yellow	Light gray tipped cream	Light gray tipped white	Light gray tipped white

TABLE 3. Ranges and mean (± standard deviation) of opponent color coordinates (L, a, b) reflected from plumage areas

	USNM 631622* ♂	USNM 631501 ♂	USNM 631524 Ψ	USNM 631537 Ψ
Upper Throat
L	56.6-62.1 59.9±2.2	60.1-64.3 62.8±2.1	63.9-66.0 65.1±0.8	69.5-72.8 71.8±1.3
a	17.3-23.7_21.8±2.6	18.5-23..7 20.7±2.3	16.2-18.6 17.3±0.9	4.8-7.1 5.7±0.9
b	66.9-74.7 70.0±3.3	69.7-73.1 71.1±1.4	68.6-72.8 71.2±1.7	65.2-68.0 66.7±1.2
Crown
L	22.6-23.1 22.8±0.2	20.3-22.0 21.2±0.8	23.6-24.2 23.8±0.3	23.2-25.0 24.1±0.7
a	0.1-0.5 0.3±0.1	0.2-0.6 0.4±0.2	-0.1-(+0.2) 0.1±0.1	0.2-0.4 0.3±0.1
b	1.3-2.7 2.2±0.7	1.9-2.7 2.3±0.3	7.2-7.6 7.4±0.2	3.9-4.9 4.6±0.5
Back
L	27.0-28.0 27.5±0.5	27.6-29.1 28.4±0.7	27.0-28.1 27.4±0.4	27.6-28.6 28.0±0.4
a	-0.9-(+1.3) 0.1±0.8	-0.8-(-0.5) -0.6±0.2	-0.4-(+0.2) -0.6±0.2	0.2-0.6 0.5±0.2
b	9.1-14.0 11.8±2.0	13.8-16.4 15.1±1.2	12.1-13.3 12.6±0.5	12.6-15.9 14.2±1.5
Belly
L	80.2-82.2 81.1±0.8	80.7-83.3 82.0±1.2	81.8-84.3 82.5±1.8	79.4-81.4 80.6±0.8
a	-3.1-(-0.8) -2.2±0.9	-2.7-(-1.7) -2.4±0.4	-3.2-(-1.9) -2.7±0.6	-3.6-(-3.3) -3.5±0.1
b	40.3-45.3 42.9±1.9	32.8-35.9 34.3±1.3	21.2-31.6 27.8±4.3	22.3-28.0 25.4±2.7