RIELLA

Figure 1. Riella cossoniana: (A) habit of male plants, (B) female plants and (C)  ellipsoid involucres with 8 broad wings and blunt apices.

Spores 68–93 × 60–90 μm including spines, light brown, globose, round in outline. Distal face densely covered with 14–22 irregular rows of spines across diameter and interspersed smaller papillae, distance between spines 1.6–6.9 μm, and (31) 39 (46) projecting spines at periphery at the equatorial plane. Spines (2.7) 4.11 (6.0) μjm long (1.2) 2.4 (4.4) μm wide, with truncate apices, basal membranes interconnecting spines below restricted to distal pole, 0.3–1.3 μm high, forming imperfect reticulations and not defining areolae, absent from other parts of distal face; basal membranes at the equatorial plane indistinct. Proximal face concave, triradiate mark indistinct, surface of proximal face rugose.

Habitat and distribution: seasonal brackish water ponds in arid or semiarid environments. Widely distributed in coastal countries of the Mediterranean area and western Asia. Scattered populations have been recorded in Algeria (Trabut 1887, Maire 1937, Jelenc 1957, Frahm 1978), France (Martinez et al. 2014), India (Patel 1977b), Iraq (this study), Israel (Lipkin & Proctor 1975), Jordan (Ros et al. 2007), Spain (see below), Uzbekistan (Porsild 1902, 1903), and Kazakhstan (Ladyzhenskaja & Obuchova 1956, Obuchova 1961, Ladyzhenskaja & Fedorova-Shaknmundes 1976). Reports from Tunisia and Morocco are excluded based on their lack of sufficient support.

Notes:―Most of the records occur in the western Mediterranean. In this area, the Iberian Peninsula concentrates the largest number of populations where it is currently known from seven mainland Spanish provinces: Alicante (Ros 1987), Barcelona (Seguí et al. 2005, Seguí & Pérez 2006), Guadalajara (Cirujano et al. 1988), Málaga (Ortega-González et al. 2002), Murcia (Ros et al. 1996, Cano et al. 2004), Toledo (this study), and Valencia (Segarra-Moragues et al. 2014). This pattern may reflect a higher abundance of suitable habitats for this species in this area, a stronger sampling effort in this area or both of these possibilities.

In fact, our field sampling conducted in Segarra-Moragues et al. (2014) revealed four new Iberian populations. Three of them, in the eastern coast of Valencia, bridge the gap between the southeastern (Alicante province) and the northeastern (Barcelona province) populations. The fourth new population in Central Spain (Toledo province). These three new records considerably extend the Iberian range of R. cossoniana.

Similarly, our study revealed that some previous Iberian records were misattributed to R. cossoniana. The record from a southwestern population (Sevilla province; Cirujano et al. 1992, 1993) corresponds to R. mediterranea, whereas existing records from Grand Canary in the Canary Islands by Van Dort & Nieuwkoop (2003) correspond to R. echinata.

Our analyses, agreeing with Lipkin & Proctor (1975), do not support the distinctness of R. cossoniana. from R. paulsenii. Riella cossoniana is readily distinguished from the monoicous R. affinis and R. heliospora by its dioicous sexual condition and by radically different spore morphology. From the dioicous species it differs in the larger, continuous wings of female involucres, that in combination with spore ornamentation features allow its separation from the remaining five species recognised until the review in Segarra-Moragues et al. (2014).