Christella distans (Hook.) Holttum

Fawcett, Susan & Smith, Alan R., 2021, A Generic Classification of the Thelypteridaceae, Fort Worth, Texas, USA: BRIT Press : 36

Constituent species and infrageneric taxa (generally following Holttum 1982; Li et al. 2013).—* Christella acuminata (Houtt.) Lév. ; C. adenopelta Holttum ; ** C. arida (D. Don) Holttum ; C. balansae (Ching) Holttum ; ** C. boninensis (Kodama ex Koidz.) Holttum ; C. burmanica (Ching) Holttum ; C. buwaldae (Holttum) Holttum ; * C. calcarea D.Glenny , sp. ined.; C. callensii (Alston) Holttum ; ** C. calvescens (Ching) Holttum ; C. carolinensis (Hosok.) Holttum ; * C. chaseana (Schelpe) Holttum ; C. clarkei (Bedd.) Holttum ; * C. conspersa (Schrad.) Á. LÖve & D. LÖve; ** C. crinipes (Hook.) Holttum ; C. cuneatus Ching ex K.H. Shing ; C. cylindrothrix (Rosenst.) Holttum ; * C. dentata (Forssk.) Brownsey & Jermy ( Fig. 2J ); * C. ensifera (Tagawa) Holttum ; C. euphlebia (Ching) Holttum ; * C. evoluta (C.B. Clarke & Baker) Holttum ; C. fukienensis (Ching) Holttum ; * C. gretheri (W.H. Wagner) Holttum ; * C. guamensis Holttum ; * C. gueintziana (Mett.) Holttum [several authors, e.g., Schelpe (1964), Holttum (1974a), and Roux (2009, 2013), have used the altered spelling “ gueinziana ”, but this is impermissible]; C. gustavii (Bedd.) Holttum [placement in Christella disputed by Li et al. 2013]; * C. harveyi (Mett.) Holttum ; C. harveyi var. connivens Holttum ; * C. hispidula (Decne.) Holttum ; C. hokouensis (Ching) Holttum [placement in Christella disputed by Li et al.]; * C. jaculosa (Christ) Holttum ; C. jinghongensis (Ching ex K.H. Shing) A.R. Sm. & S.E. Fawc. ; C. kendujharensis S.K. Behera & S.K. Barik. ; C. kumaunica Holttum ; * C. latipinna (Benth.) H. Lév. ; C. lebeufii (Baker) Holttum ; C. microbasis (Baker) Holttum ; C. minima Holttum ; C. modesta Holttum ; C. moluccana M. Kato ; C. mutifrons ( C. Chr.) Holttum; C. namburensis (Bedd.) Holttum ; C. nana Holttum ; ** C. nanxiensis (Ching ex K.H. Shing) A.R. Sm. & S.E. Fawc. ; C. pacifica Holttum ; * C. papilio (Hope) Holttum ; C. papyracea (Bedd.) Holttum ; * C. parasitica (L.) Lév.; C. peekelii (Alderw.) Holttum ; C. perpubescens (Alston) Holttum ; C. procera (D. Don) Mazumdar , with heterotypic synonym C. appendiculata (C. Presl) Holttum (= Thelypteris appendiculoides Fraser-Jenk. ); C. prolixa (Willd.) Holttum ; C. pseudogueintziana (Bonap.) Alston; C. rupicola (Hosok.) Holttum ; ** C. scaberul a (Ching) Holttum; C. semisagittata (Roxb.) Holttum ; C. shimenensis (K.H. Shing & C.M. Zhang) A.R. Sm. & S.E. Fawc. ; * C. siamensis (Tagawa & K. Iwats.) Holttum ; C. sledgei (Fraser-Jenk.) Ranil ; C. subdentata Holttum ; ** C. subelata (Baker) Holttum ; C. subjunc ta (Baker) Holttum; * C. subpubescens (Blume) Holttum ; C. taprobanica (Panigrahi) Holttum ; C. timorensis Holttum ; C. wulingshanensis (C.M. Zhang) A.R. Sm. & S.E. Fawc. ; C. zeylanica (Fée) Holttum.

Excluded names.— Dryopteris albociliata Copel. [= C. parasitica ]; Dryopteris assamica Rosenst. [= C. cylindrothrix ]; Cyclosorus benguetense Copel. [= C. hispidula ]; Polystichum benoitianum Gaudich. [= Sphaerostephanos benoitianus (Gaudich.) Holttum—Holttum thought it possibly related to Strophocaulon invisum (G. Forst.) S.E. Fawc. & A.R. Sm. ]; Nephrodium biauritum Bedd. [= C. lebeuffii]; Dryopteris contigua Rosenst. [= C. hispidula ]; Nephrodium didymosorum Parish ex Bedd. [= C. parasitica ]; Dryopteris euaensis Copel. [= C. harveyi ]; Nephrodium eurostotrichum Baker = Christella distans (Hook.) Holttum , incertae sedis; Cyclosorus falcatulus (Christ) Copel. [= C. hispidula ]; Dryopteris hirtopilosa Rosenst. [= C. hispidula ]; Cyclosorus jerdonii Ching (excluded from Christella by Holttum 1976b: 336); Dryopteris meeboldii Rosenst. [= C. malabariensis ]; Dryopteris mindanaensis Christ [= C. dentata ]; C. molliuscula (Wall. ex Kuhn) Holttum [= Pseudocyclosorus canus (Baker) Holttum & Grimes ]; C. multiauriculata Punetha [= C. dentata ]; Thelypteris novae-hiberniae Holttum [= C. harveyi ]; Polypodium nymphale Forst. [= C. dentata ]; Aspidium obliquatum Mett. [= C. prolixa ]; Aspidium procurrens Mett. [= C. parasitica ]; Dryopteris pseudoamboinensis Rosenst. [= C. subpubescens ]; Nephrodium quadrangulare Fée [= C. hispidula ]; Dryopteris repandula Alderw. [= C. hispidula ]; Cyclosorus subaridus Tatew. & Tagawa ex Tagawa [= Christella jaculosa ]; Dryopteris submollis Alderw. [= C. dentata ]; Dryopteris sumatrana Alderw. [= C. subpubescens ]

Excluded species.— Three Hawaiian endemic species treated in Christella by Holttum (1977b) and Palmer (2003), Christella boydiae , C. cyatheoides and C. wailele are here transferred to the genus Menisciopsis . Based on a photo of the type of Christella burundensis Pic.Serm. , and notes on the specimen by Holttum, this is not a Christella , and may be Pelazoneuron kunthii (Desv.) A.R. Sm. & S.E. Fawc. ; it has free veins and the proximal pinnae are not reduced. If that species, it is likely introduced and not native to Burundi.

Incertae sedis.— Christella afzelii (C. Chr.) Holttum. Based on an image of the type, this appears to be bipinnate; veins are free and sometimes forked. It is unlikely to be a Christella .

Several Afro-Madagascan species (represented by Pneumatopteris humbertii and Christella distans in Fawcett et al. in press) are more closely related to Pseudocyclosorus and Trigonospora than to Christella s.s. Holttum (1976b) considered Christella distans the most aberrant species in Christella , in part because of the swollen aerophores; we agree, and its taxonomic placement remains uncertain. Two other species, Christella friesii (Brause) Holttum and C. guineensis (Christ) Holttum , may also belong to the Pseudocyclorosus + Trigonospora clade. Based on the original description ( Rakotondrainibe & Jouy 2011) and images of the type ( P!) of Christella darainensis Rakotondr. , we note that the veins are free with the proximal one of a pair running to the sinus, the adjacent vein meeting the margin above the sinus, the rhizome is erect, and the stipe base scales are ovate and glabrous, unlike those of Christella , suggesting it may be more closely related to Trigonospora . The African Thelypteridaceae have been the most difficult taxonomically and have been subject to the greatest taxonomic upheaval as a result of our phylogenetic study (see Menisorus and Pneumatopteris for further discussion). This morphologically variable, and poorly studied species group cannot be confidently placed; additional molecular sampling and study of herbarium material will be necessary before taxonomic changes are made.

Figures

FIG. 2. Morphology of the Thelypteridaceae.A. Coryphopteris kolombangarae, SITW07554 (TAIF), glandular indusia.B. Goniopteris yaucoensis, Proctor 43584 (US), stellatehairs along adaxialcosta.C.Pneumatopterisglandulifera,SITW11069 (TAIF),peg-like aerophoresat pinna bases.D.Sphaerostephanospolycarpos,SITW11070 (TAIF),marginally glandular indusia.E.Sphaerostephanos doodioides,SITW05702(TAIF),setoseindusia,spherical glands on indusia,sporangia,and laminar tissue. F. Goniopteris reptans, Wright 813 (US), sori with shriveled, setose indusia, some hairs furcate. G. Macrothelypteris polypodioides, SITW11122 (TAIF), stipe scales. H. Hoiokula pendens, Hobdy 2664 (UC), setulose sporangia. I. Plesioneuron imbricatum, SITW05370 (TAIF), exindusiate sori, sporangia with spherical glands. J. Christella dentata, SITW10525 (TAIF), shriveled,setulose indusia.K. Sphaerostephanos heterocarpos SITW11079 (TAIF),abruptly reduced proximal pinnae,adaxial surface with acicular hairs.L. Coryphopteris subbipinnata, SITW11667 (TAIF),appressed stipe base scales,these marginally setulose.All photos by Cheng-Wei Chen except B,F,and H by Susan Fawcett.