Pyxine cognata Stirt

Yang, Mei-Xia, Wang, Xin-Yu, Liu, Dong, Zhang, Yan-Yun, Li, Li-Juan, Yin, An-Cheng, Scheidegger, Christoph & Wang, Li-Song, 2019, New species and records of Pyxine (Caliciaceae) in China, MycoKeys 45, pp. 93-109 : 93

Pyxine cognata Stirt

= Pyxine berteriana var. himalaica D.D. Awasthi

Description.

Upper surface white to whitish-grey or grey-brown; isidia and soredia absent; medulla orange-yellow to orange; lower surface black in the centre, paler towards the margin; apothecia common, (0.3) 0.5-1.0 (1.5) mm wide; internal stipe upper part orange, K+ purple, P–; lower part yellow or much paler than upper part, K–, P–. Upper cortex K–, UV+ yellow, medulla K– or K+ pale red, C–, P– or P+ orange; containing lichexanthone (major), triterpenes, unknown pigment (minor) (detected by TLC).

Habitat and distribution.

Growing on bark of Quercus and Juglans spp. Range 1090-2230 m elevation in semi-arid environments. Worldwide distribution: India ( Awasthi 1982), Brazil (Aptroot 2014), Thailand ( Mongkolsuk et al. 2012) and Australia ( Elix 2009); newly recorded in China.

Notes.

Pyxine berteriana var. himalaica was described by Awasthi (1982) as a variety based on the pale yellow to yellow medulla and a narrow distribution from the Himalayan region and central India. Pyxine cognata is very similar to P. berteriana var. himalaica in the presence of lichexanthone, the pigmented medulla and the lack of isidia and soredia. However, Pyxine cognata is distinguished by a faint pruina on the lobe tips, deep yellow to rust coloured medulla and slightly larger spores, as well as for being widely distributed in tropical regions. Therefore, the morphological and ecological differences between these two species are minor. In this study, we collected specimens of both species and found that they have a similar ecology and distribution pattern. Phylogenetic analysis inferred that Pyxine berteriana var. himalaica is clustered with P. cognata with a high support value (MLBS = 100%, PP = 1.00). Based on the combination of molecular, morphological and ecological information, we propose P. berteriana var. himalaica as a synonym for P. cognata .

Pyxine cognata is most similar to P. berteriana in that it contains lichexanthone, lacks isidia and soredia and has a pigmented medulla; however, P. cognata can be distinguished by the presence of lichexanthone in the cortex, an orange medulla and an orange-yellow internal stipe of apothecia with K+ purple. In comparison, P. berteriana has a pale yellow to yellow medulla and the internal stipe is pale yellow to yellow. ( Kalb 1987). Despite the broad similarities, these species are not closely related; P. cognata seems to share a unique ancestor with P. subcinerea . Pyxine subcinerea differs in that it has marginal soralia and obscurascens-type apothecia ( Elix 2009). (Fig. 1).

Selected specimens examined (KUN).

CHINA: SICHUAN PROVINCE: Miyi Co., Malong north slope, 2100 m elev., on Carya spp., 5 Jul 1983, L. S. Wang 83-698; Dukou Co., Dabaoding, 1900 m elev., 21 Jun 1983, L. S. Wang 83-212. YUNNAN PROVINCE: Yuanmou Co. Langbapu Forest Soil, 1612 m elev., 25°41'01.76"N, 101°41'25.78"E, on branch, 21 Apr 2014, c14-43569, 14-43539; Yongren Co., from Menghu to Wanma, 1543 m elev., 26°13'45.15"N, 101°25'56.86"E, 3 Dec 2013, L. S. Wang et al. 13-40767.