Psittinus, Blyth, 1842

Smith, Brian Tilston, Thom, Gregory & Joseph, Leo, 2024, Revised Evolutionary And Taxonomic Synthesis For Parrots (Order: Psittaciformes) Guided By Phylogenomic Analysis, Bulletin of the American Museum of Natural History 2024 (468), pp. 1-87 : 52-55

Psittinus

The mono- or ditypic genus Psittinus of continental Southeast Asia, Borneo, and Sumatra is morphologically divergent relative to Psittacula . Psittacula sensu lato are slender bodied, long-tailed birds perhaps recalling Polytelis , whereas Psittinus has a short, rounded tail and a stocky body recalling the “true parrots” of older literature such as Geoffroyus . Largely green, various populations have blue or black distributed in distinctive patches on the head and dorsal surface. The bill is bicolored, the maxilla being red and the mandible black. Traditionally treated as comprising one species with three subspecies, a recent trend has been to elevate P. c. abbotti, found on two islands of western Sumatra, to species rank on the basis of its larger size and different pattern of sexual dimorphism in plumage (del Hoyo et al., 2014; Eaton et al., 2016; Gill et al., 2023).

The phylogenomic trees show discordance between the concatenated and species tree topologies, but the trees certainly support the need for a taxonomic revision. A prominent difference between the Braun et al. (2019) tree and both the phylogenomic trees was in the placement of Psittinus . Braun et al. (2019) found that Psittinus was sister to a clade containing Tanygnathus , Psittacula longicauda , Psittacula alexandri , and Psittacula derbiana . In contrast, the phylogenomic tree showed that Psittinus was strongly supported as sister to the entire clade containing Psittacula / Tanygnathus (fig. 10), and that pattern was also recovered in the species tree. These two basal lineages shared a common ancestor 10.5 Mya (6.2– 13.7; fig. 10). The position of Psittinus does not impact the proposed generic revision of Braun et al. (2019), but it is important for understanding the evolutionary history of the clade.

For the remaining lineages, the phylogenomic tree favors fewer new monophyletic genera. It supports Himalayapsitta (roseata, cyanocephala, himalayana, and finschii ) as represented by a clade stemming from the basal node in the entire Psittacula-Tanygnathus group 10 Mya (5.9–13; fig. 10). Braun et al. (2019) further proposed Nicopsitta , Palaeornis , and Alexandrinus to account for the nonmonophyly among the group more broadly. Our phylogenomic analyses place all the species that would be subsumed in the first two of these genera (calthrapae, columboides, wardi , eupatria) as well as eques in a clade for which we advocate recognition under the oldest available name, Palaeornis Vigors, 1825 . The generic variation characterized by Braun et al. (2019) was reflected in the relatively deep crown age of Palaeornis at 8.2 Mya (4.8–10.8; fig. 10). Note that if the phylogenetic position of extinct Mascarinus mascarinus (Linnaeus, 1771) found by Podsiadlowski et al. (2017) is confirmed then this species would also be placed and rounded tails of these birds are likely derived within Palaeornis , which is the older generic name. traits, but this depends on the position of Psitti- Braun et al. (2019) inferred longicauda with weak nus. Tanygnathus gramineus occurs only on Buru support to be sister species to derbiana / alexandri ( Moluccas, Indonesia). It is monotypic and and accordingly suggested placing longicauda in a extremely rare in collections and we have been monotypic genus, Belocercus S. Muller, 1847 . We unable to sample it. The other species all show have found support for that relationship among geographic variation expressed with up to six these species in the phylogenomic tree (UFBS = described subspecies. 94%; fig. 10). This includes caniceps, which was not Provost et al. (2018) and Braun et al. (2019) sampled in Braun et al. (2019), as sister to longi- each inferred relationships for Tanygnathus , but cauda in our tree. We dated the basal divergence each of those studies drew on samples of two of Psittacula sensu stricto ( derbiana , alexandri , lon- species ( T. sumatranus , T. megalorhynchos ), gicauda, caniceps) at 6.8 Mya (3.8–9.4; fig. 10). whereas Arndt et al. (2019) and the present study Accordingly, we favor retention of the two sister included T. sumatranus . The best estimation of species pairs that comprise there four taxa, (longi- phylogenetic relationships among the other specauda, caniceps, alexandri , and derbiana ) within cies based on our analyses and that of morphol- Psittacula Cuvier, 1800 (type species is Psittacus ogy (plumage, iris color) and mitochondrial alexandri Linnaeus, 1758 ; see Schodde et al., 2012; DNA sequences (Arndt et al., 2019) was that T. ICZN, 2014), rendering Belocercus synonymous megalorhynchos and T. lucionensis were sister with it. However, the species tree has longicauda species, and that T. sumatranus sensu lato was and caniceps (the latter not sampled by Braun et al., sister to both (fig. 10). This topology was not 2019) as sister to Tanygnathus (LPP = 1.0). This comparable to other trees. The position of T. relationship, if eventually confirmed, could be lucionensis in the species tree was unreliable expressed by the adoption of Belocercus to avoid a because the sample was of lower quality. Despite paraphyletic Psittacula , but we do not recommend the lower diversity of Tanygnathus , the clade had its adoption yet. a crown age of 6.0 Mya (3.4–7.9; fig. 10).

Braun et al. (2019) also found some cases of Arndt et al. (2019) argued on grounds of morparaphyletic species, derbiana being nested phology (plumage, iris color) and cytochrome b within alexandri , and echo within krameri. sequences from mitochondrial DNA that Philip- Because the sampling of the entire group has pine populations of T. sumatranus should be relied on using captive birds, samples from wild elevated to species rank as T. everetti . We agree birds will be required to verify these patterns. We that further work is needed to accurately place T. do not yet advocate placing derbiana within alex- e. burbidgii (Sulu Islands) and T. s. sangirensis andri but urge closer study. (Talaud Islands) before species limits in T. sumatranus sensu lato are resolved. Tanygnathus

Tanygnathus are predominantly green, round- Psittacellinae tailed parrots with large or massive bills, and in most species, at least partly red. The four usually recognized species (see below) are distributed in Psittacella the Philippines and Indonesia. The genus is nested The tiger parrots ( Psittacella ) are stocky, small deeply within Psittacula sensu lato, so the large bill to midsized with short round tails ( Forshaw and Knight, 2010). The English name tiger-parrot is derived from the yellow-and-black barring in the chest (upper ventral) plumage in females of three of the four species. There are two small and two larger species, clearly forming two species pairs that were reflected in our phylogeny (fig. 11).

The clade is on a deep branch, sharing a common ancestor with the clade containing the subfamilies Platycercinae , Loriinae , and Agapornithinae 20.6–33.5 Mya (fig. 1). Across this relatively long evolutionary period, there are only four species that diversified in the mountains of New Guinea. Phylogenetic relationships are stable and consistent across concatenated and species tree approaches in the phylogenomic data. Prior phylogenetic work only sampled P. brehmii and P. picta ( Provost et al., 2018) . Psittacella modesta and P. madaraszi are sister and have olive-brown heads with green backs. The other sister pair, P. brehmii and P. picta , have black barring on their backs. The crown age of Psittacella , 11.3 Mya (6.8–14.5; fig. 11), was among the oldest of all parrot genera, as are the species-level divergence time estimates. One subspecies of P. picta , P. p. lorentzi, has occasionally been elevated to species rank ( Mayr, 1941; del Hoyo and Collar, 2014) based on plumage differences, Mayr (1941) only further noting that they “form a superspecies.” Gregory (2017) commented that they differ “significantly in plumage,” lorentzi seeming “as distinct from Painted [ P. picta ] as Modest [ P. modesta ] and Madarasz’s Tiger-Parrots [ P. madaraszi ] are from each other.” More recently, Collar et al. (2020) imply that they will retain the two species arrangement, although at the time of our writing (11 May 2024) had not yet not employed it. We agree with Beehler and Pratt (2016) in stressing that this is premature until the nature of any contact where P. p. lorentzi and P. p. excelsa meet is explored, especially with genetic data. Beehler and Pratt (2016) noted that the likely area of contact, near the Strickland River gorge, is a barrier for a number of montane species. The details of this case, to reiterate, need further study.

We know of no proposal to separate the large- and small-bodied species pairs of Psittacella into two genera (fig. 12). Given their ages, this is not without merit. That differently sized but otherwise extraordinarily similar species with a sister-group relationship should be placed in different genera finds support elsewhere in Aves, e.g., the meliphagid genera Entomyzon and Melithreptus . In that case, there is no extant species of clearly intermediate size whereas in Psittacella the four species more smoothly intergrade in size between extremes. Further, subclades in Psittacella cannot be diagnosed by yellow-and-black barring in the chest of females because three out of four of the species have the character state. We refrain from breaking up Psittacella here primarily for those reasons.