Euphorbia sect. Anisophyllum Roep.

Mugnai, Michele, Lazzaro, Lorenzo, Nuzzo, Luca Di, Foggi, Bruno, Viciani, Daniele & Ferretti, Giulio, 2021, Synopsis of Euphorbia section Anisophyllum (Euphorbiaceae) in Italy, with an insight on variation of distribution over time in Tuscany, Phytotaxa 485 (1), pp. 1-65 : 10-12

Euphorbia sect. Anisophyllum Roep. in Duby, Bot. Gall., pars prima: 412. 1828.

Type (lectotype, designated by Wheeler 1941: 110):— Euphorbia peplis L.

≡ Anisophyllum Haworth (1812: 159) , non Jacquin (1763: 283), nom. illeg.

≡ Chamaesyce Gray (1821: 260)

≡ Euphorbia subg. Chamaesyce (Gray) Cesalpino ex Reichenbach (1841: 193) , non Raf. (1817: 119), nom. illeg.

= Xamesike Rafinesque (1838a: 115) . Type (lectotype, designated by Wheeler 1941: 111):— Xamesike vulgaris Rafinesque (1838a: 115) , nom. illeg. (≡ Euphorbia chamaesyce L.)

Description:—Perennial or annual herbs (rarely shrubs or subshrubs). Branches many, dichotomous, prostrate or ascending; main shoot usually aborts above the cotyledon node and dichotomous lateral branches. Leaves opposite, glabrous to hairy, base often asymmetrical; veins sometimes visible on leaf blades (Kranz anatomy); margins entire to serrate; stipules interpetiolar, connate to distinct, linear, or subulate-triangular. Cyathia solitary at bifurcation of branches or clustered in axillary cymes; glands 4, rarely 5–7; appendages petaloid when present; styles 3, free or connate at the base, tip bifid; ovary and capsule glabrous to pubescent. Seed surface smooth, with transverse ridges, or irregularly wrinkled; mostly 4-angled, ecarunculate. C2, C3, or C4 photosynthesis ( Yang et al. 2012).

Historical background:—Roeper in Duby (1828) was the first botanist that correctly considered Anisophyllum as a section of the genus Euphorbia , on the basis of distinctive morphological characters. Some authors (e.g., Prokhanov 1933, Burch 1965, Benedì & Orell 1992a, Burger & Huft 1995, Benedì 1997, Hügin 1998b, Jercinovic 2007, Banfi & Galasso 2010) recognised this clade as a separate genus, Chamaesyce , for its morphological distinctness from other species of genus Euphorbia . Nevertheless, molecular studies (e.g., Steinmann & Porter 2002, Bruyns et al. 2006, Zimmermann et al. 2010) suggest a treatment at infrageneric level ( Yang & Berry 2011), as for other Euphorbia sections i.e. E. sect. Poinsettia ( Graham 1836: 412) Baillon (1858: 284) . Currently, the former genus Chamaesyce , whose monophyly is well supported according to Yang et al. (2012), corresponds to Euphorbia subg. Chamaesyce sect. Anisophyllum . All the species considered in the present study are included in Euphorbia subsect. Hypericifoliae Boiss. in Candolle (1862: 20) ( Yang et al. 2012), even though E. sect. Anisophyllum includes also E. subsect. Acutae Boiss. in Candolle (1862: 18).

General note:—Plants of warm, arid and semi-arid vegetation or disturbed habitats, and summer annuals of temperate areas. Nearly worldwide, from sea level to 4,000 m a.s.l. ( Yang et al. 2012).

. Euphorbia berteroana Balb. ex Sprengel, Syst. Veg. , ed. 16 3: 794. 1826.

Type (lectotype, designated by Mugnai et al. 2020):— FRANCE ( GUADELOUPE). E. quadristipula Berter [o] ex Guadalupa 1819, Bertero s.n. ( TO!)

≡ Chamaesyce berteroana (Balb. ex Spreng.) Millspaugh (1909: 303)

≡ Anisophyllum berteroanum (Balb. ex Spreng.) Klotzsch & Garcke in Klotzsch (1860: 32)

= Euphorbia bicephala Bertoloni (1844a: 435) . Type:— DOMINICAN REPUBLIC. Euphorbia origanoides L. S.D. Bertero legit in Domingo; misit Balbisius, 1822, Bertero s.n. (holotype, BOLO image!, see Mugnai et al. 2020)

– Euphorbia origanoides Balb. , nom. nud. in Bertoloni (1844a: 435) non L. (1753: 453)

= Euphorbia stipitata Millspaugh (1900: 65) . Type:—not found (holotype sheet 61782 in F, see also Burch 1965). Isotype F0056615 image! (see Burch 1965).

Description:—Herbs, annual. Stems decumbent to ascending, brownish, short-tomentose. Leaves opposite; stipules distinct to slightly connate, linear, dentate, 1 mm; petiole 1 mm; blade ovate-elliptic to oblong, yellowish green, 5–15 × 3–8 mm, base obliquely rounded, margin crenulate or blunt-serrate, apex rounded, short pilose. Cyathia in dense terminal leafless capitate cymes; peduncle short. Involucre narrowly campanulate, 0.7 mm diameter, with triangular lobes exceeding glands, strigose; glands 4, subcircular, 0.2 mm diameter; appendages white, shorter than lobes. Staminate flowers 5–8, 1 mm long at maturity, androphores glabrous. Pistillate flowers: exserted from involucre; ovary pilose; styles upright, 0.4–0.6 mm long, joined at base, bifid for ½ of length. Capsules elliptic, shallowly 3- lobed, 1.5 × 1.5 mm. Seeds brown, chestnut or grey, long-cuneiform, strongly 4-angled in cross-section, 0.9 × 0.4 mm, transversely ridged ( Burch 1965; Rzedowski & Rzedowski 2004).

Iconography:— Bertoloni (1844a: pl. 23 fig. 1), Fig. 5 .

Chromosome number:—n = 7 ( Subils 1977).

Ecology:—Nitrophyte proper to ruderal communities of trampled biotopes and disturbed shrublands ( Rzedowski & Rzedowski 2004).

Chorology:— Mexico, Caribbean and South America.

Alien status:—Recorded by mistake in Italy ( Galasso et al. 2018b). To date there is no evidence of occurrence outside the native range.

Occurrence in Italy:—Absent. Recorded by mistake in SAR ( Guarino & La Rosa 2019) and SIC ( Galasso et al. 2018b).

Taxonomic annotations:— Euphorbia berteroana was collected by Carlo Giuseppe Bertero, who named this species Euphorbia quadristipula . Nevertheless, he never published the description of this name, and thus it is considered as invalid (see Mugnai et al. 2020). Euphorbia berteroana is not listed by Galasso et al. (2018a), but it is mentioned by Pignatti (1982) and Pignatti et al. (2017) as a species similar to E. nutans , observed in SIC at the end of XIX century. Moreover, Guarino & La Rosa (2019) list this species as present in SAR but not in SIC, presumably due to an erroneous localization of data (considering that in the same work only one specimen collected in Italy is showed, and it is the one from SIC by Lojacono: P00630120). However, as already stated by Galasso et al. (2018b), records of E. berteroana from Italy are erroneous and should be referred instead to E. ophthalmica . These species are similar, but E. berteroana can be easily recognized by capsules slits.

Bertoloni published the name E. bicephala twice in 1844 (in Bertoloni 1844 a, 1844b). We checked both contributions, but we could not find any clear element allowing to establish which publication was published previously. Nevertheless, following Stafleu & Cowan (1983), Bertoloni (1844b) seems to have been published after Bertoloni (1844a) as a reprint.

In the protologue, Millspaugh (1900) cited explicitly a single specimen of Euphorbia stipitata (sheet 61782 in F) that, accordingly, should be considered as the holotype. We could not find this sheet in F, but we retrieved a sheet identified as isotype by Derek Burch in 1964. Indeed, already this author reported that he was not able to locate the holotype ( Burch 1965).

Figures

FIGURE 5. Euphorbia berteroana:A) exsiccatum from Guadaloupe preserved at TO, B) detail of terminal glomerule with short peduncle (scale = 0.5 mm).