Chlorospingus semifuscus semifuscus, 1873

Sánchez-Nivicela, Manuel, Avendaño, Jorge Enrique, Sánchez-Nivicela, Juan C., Torres, Ana, Fuchs, Jérôme, Bird, Bentley & Bonaccorso, Elisa, 2021, A taxonomic assessment of Chlorospingus flavopectus phaeocephalus and Chlorospingus semifuscus (Passeriformes: Passerellidae), including the description of a new subspecies, Zootaxa 5057 (2), pp. 151-180 : 165

Chlorospingus semifuscus semifuscus “ Chimborazo ” morph

Plumage and iris coloration (n = 6, 5 males and 1 unsexed). — Throat color and pattern: in general, it can be perceived as something between light buff (f. 17) and cream color (f. 19) mixture; some feathers are pale smoke gray (C.44) and drab-gray (C.119D), with olive-yellow (C.52) scattered barbules with the presence of glaucous (C.79) speckles. Malar region : some olive-yellow (C.52) barbules with a slight glaucous (C.79) moustachial stripe can be seen from lateral view. Pectoral band: close to spectrum yellow (C.55) and partially olive-yellow (C.52) on flanks near shoulder. Belly : transition from whitish plumage with light neutral gray (C.85) and pale neutral gray (C.86) presenting some olive-yellow (C.52) scattered barbules. Iris coloration: In the field, the iris of this population is generally pale yellow. However, the specimen collected during this research ( MECN 9637 ) presented a combination of iris colors, from pale yellowish in the inner border of the iris, changing to very pale yellow-pinkish in the outer border of the iris, to red in the ciliary margin. When thoracic compression was applied, the entire iris turned a color similar to flesh ocher (C.132D). However, the labels of four specimens collected by Stolzmann and Siemiradski in 1883 contained the species epithet “ erythrops,” which means red eye, and three red color-related descriptive terms when collected, such as: brick-red ( NHMUK 1885.6.12.855), flesh color ( MNHN 1999-2693 , USNM 159864 ), and blood-red ( USNM97741 ). Postmortem iris colors were described as “flesh or ocher-red,” while in juveniles were described as grayish-brown ( Berlepsch & Taczanowski 1884) .

Breeding.—A juvenile female was collected in Cayandeled or Chimbo junction by J. Stolzmann and J. Siemiradski, but the specific date of that skin is difficult to discern. They collected in January, February, March, and September 1883 ( Berlepsch & Taczanowski 1884).

Distribution.—Along the Chimbo River headwaters and tributaries, in Bolívar and Chimborazo provinces, southwards the junction and drainage of the Chimbo and Chanchán rivers ( Fig. 1 ). This population could be restricted to the remaining suitable habitat in this region, which is surrounded by agricultural land, farms, and cattle pasture. According to the skin label (NHMUK 1885.6.12.856), the site where the first individual of this population was collected is Chillanes, in Bolívar Province. This locality is at a higher elevation, but not distant from the Chimbo-Chanchán river junction and Pallatanga town in Chimborazo Province, where L. Fraser spent a fair time during his expedition in Ecuador. It is difficult to elucidate the exact original locality of this specimen, since no other details are specified by Sclater & Salvin (1877). However, it may be located in the same general region and habitat where other similar individuals of C. “ Chimborazo ” have been found later in the same province. After two field expeditions visiting suitable habitat in the Cañar River drainage and Molleturo-Naranjal road area, we did not find representatives of this population or any of the Chlorospingus populations reviewed here ( Fig. 1 ). This population might be restricted on its southern limit by the Cañar River drainage. We cannot estimate the altitudinal range of this population precisely. Still, the altitudes where specimens of this group were collected are Cayandeled (1372 m), Surupata (1128 m) ( Berlepsch & Taczanowski 1884), and Santa Rosa de Chilicay (this study ~ 1217–1227 m; Fig. 1 ). We consider this population uncommon and very localized.

Taxonomic status.—Given the uncertainties about the origin and nature of C. “ Chimborazo ” and the results of phylogenetic analyses, this population could be treated as a variant of C. s. semifuscus with yellow-olive breast band, and different iris colorations from pale yellow to variations of red. On the other hand, based on its distribution between C. s. semifuscus and C. “ El Oro,” it might comprise a stable hybrid population between these two. However, until further studies are conducted, we are inclined to support the treatment as a morph of C. s. semifuscus . A complementary taxonomic history review is available in Supplementary Material A9.

Figures

FIGURE 1. Distribution and plumage of populations of the Chlorospingus semifuscus group in the northwestern Andes down to Angamarca river, and Chlorospingus flavopectus phaeocephalus in the eastern Andes of Colombia and Ecuador with the putative southwestern populations in Ecuador. The map includes records (circles), geographic barriers (rivers, and Cajanuma Transversal Ridge), and the two sites with no records of the western populations (red crosses). Bird artwork by Carmen Lu Páez.