Cardinalis cardinalis mariae, Nelson, 1898

Silva, Héctor Gómez de, Pérez Villafaña, Mónica G., Cruz-Nieto, Javier & Cruz-Nieto, Miguel Ángel, 2020, Are some of the birds endemic to the Tres Marías Islands (Mexico) species?, Bulletin of the British Ornithologists’ Club 140 (1), pp. 7-37 : 33

NORTHERN CARDINAL Cardinalis cardinalis mariae (vs. C. c. affinis)

Coloration.—Based on 44 male and 35 female mariae vs. ten male and six female affinis, Grant (1965a) reported that 92% of males had a purple tinge to the plumage vs. 100% without any purple tinge (score 1), 100% of mariae females had cream-white abdomens vs. pale buff in 83% (score 1); and the grey chin and throat of females covered a larger area vs. more restricted white or rarely grey chin (score 2, grey is caused by ‘the black basal half of the feather showing through the overlying white feather-tips, and in island specimens the extent of white in the feather tip is reduced’).

Morphometrics.—Longer wing, tarsus and bill (especially bill length in males) (score 2) but shorter tail (score 2). Bill more bulging (consistent with Ridgway 1901 [not scored]).

Additional information.— Smith et al. (2011), Smith & Klicka (2013) and Ortiz-Ramírez et al. (2018) found reciprocal monophyly and deep genetic divergence between mariae and mainland specimens. Smith & Klicka (2013) and Ortiz-Ramírez et al. (2018) reported that small population size has accelerated molecular evolution in mariae.

Reasons for uncertainty.— Grant’s (1965a) sample of affinis was inadequate (morphometric characters were evaluated in 4– 9 males and six females, and plumage characters in ten males and six females), which is especially problematic because female plumage apparently fades considerably in specimens and males display extensive individual variation ( Van Rossem 1932). Furthermore, Baja California race igneus is as likely to be the sister species of mariae as affinis, and it was not explicitly compared by Grant (1965a) who stated only that ‘ five specimens of igneus were available too, and it was noted that [mariae] differed from both subspecies (igneus and affinis) mainly in the same way.’ Nelson (1898) in the original description of mariae described it as being closest to igneus, and at least in bill shape it is intermediate between mariae and affinis ( Ridgway 1901: 648–649). Ortiz-Ramírez et al. (2018: 726) mentioned that when analysing the haplotype network, mariae was closer to igneus than affinis, although this apparently contradicts both their own highest-probability scenario of colonisation (in their Fig. 4) and the phylogenies of Smith et al. (2011) and Smith & Klicka (2013). Therefore, this case requires further study.