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INTRODUCTION
Isoetes is a genus that belongs to Class Lycopodiopsida (Schuettpelz et al. 2016), being the only living genus from the Isoetaceae (Jermy 1990). Its diversity is over 200 species (Troia et al. 2016) distributed around the world excepting Antarctica (Troia and Greuter c2015). They are perennial herbs, aquatic, amphibious or terrestrial, with short stems similar to bulbs usually underground. Sporophylls linear, ligulate, subulate, spirally arranged, broader at the base, the ala, with sporangia solitary, sessile, naked, or covered by a total or a partial velum, heterosporous, numerous roots dichotomously branched. Some species may have stiff and blackish leaf remnants called phyllopods (Prada 1986, Jermy and Akeroyd 1993).
In the Andalusia region (southern Spain) four species are present: I. histrix Bory (sensu lato), I. durieui Bory, I. longissima Bory and I. delilei Rothm. The latter three are assessed as threatened by the regional government. Isoetes durieui and I. delilei (sub. I. setacea Lam.) are considered as vulnerable (VU) by Ley 8/2003, de 28 de octubre, de la Flora y la Fauna Silvestres of the Andalusia government and by Cabezudo and Talavera (2005). Isoetes longissima (sub. I. velata A.Braun subsp. velata) is catalogued as data deficient (DD) (Cabezudo and Talavera 2005). More recently, Decreto 23/2012, de 14 de febrero, por el que se regula la conservación y el uso sostenible de la flora y la fauna silvestres y sus hábitats includes I. delilei within the Listado Andaluz de Especies Silvestres en Régimen de Protección. In the same decree, I. durieui is incorporated in Catálogo Andaluz de Especies Amenazadas still as vulnerable. Isoetes histrix appeared as not threatened and it is the most widespread in Andalusia, although it is not occurring in Granada province. By contrast, the other species are less common. Isoetes durieui grows in Cádiz, Córdoba, Huelva, Jaén and Málaga; I. longissima grows in Cádiz, Córdoba, Granada, Huelva and Sevilla and I. delilei grows in Córdoba, Huelva and Sevilla (Cabezudo and Salvo 1987, Pérez-García et al. 2005, Delgado Vázquez and Plaza Arregui 2010, Cabezudo 2011, López Tirado et al. 2015, López Tirado 2018). Isoetes histrix and I. durieui are terrestrial plants with phyllopods and occasionally found together in the same habitat. By contrast, I. longissima and I. delilei are amphibious species without phyllopods and required a flooding period. Only Córdoba and Huelva provinces (western Andalusia) have the four species here mentioned. In fact, the preference of these species for siliceous soils and acid rocks determines the distribution along Andalusia, resulting rarer in eastern Andalusia where limestone substrates prevail. This work aims to update the distribution of the genus Isoetes in Córdoba province from southern Spain by revision of herbaria sheets, active field observations since 2012, and records from literature and databases.
MATERIAL AND METHODS
The distributional data for Isoetes concerning Córdoba province was gathered considering: (i) deposited specimens from COFC (Herbario de la Facultad de Ciencias de la Universidad de Córdoba), COA (Herbario del Real Jardín Botánico de Córdoba), MGC (Herbario de la Facultad de Ciencias de la Universidad de Málaga), SEV (Herbario de la Universidad de Sevilla) and GDA-GDAC (Herbario de la Universidad de Granada) (see Appendix), (ii) specimen surveying by the author since 2012, and (iii) choro-logical records from literature and databases such as www. anthos.es and www.gbif.es.
Herbaria sheets were revised as follows: COFC (January 8th 2019) , COA (May 13th 2020), MGC (September 7th 2020), SEV (September 18th 2020) and GDA-GDAC (December 17th 2020) . The main characters to correctly identify the species which occur in Córdoba province were related to megaspores, i.e. shape, size and especially surface ornamentation following Prada (1986). Phyllopods (leaf base) and habitat of the specimens were of interest when personally observed.
GPS coordinates of directly observed specimens were collected with a GPS Garmin Etrex 30. The observation period was carried out during the whole year, excluding summer season because at this time Isoetes usually lose the aerial portion of the plant. This information, together with herbaria sheets, led to a 1 km2 distribution map using ArcMap 10.4.1 software (ESRI 2016).
RESULTS
Field work since 2012 found 107 new localities. A total of 68 herbaria sheets were revised from herbaria located in Córdoba and surrounding provinces. Some of these herbaria sheets matched with records from databases. In total, 175 records were retrieved. The most observed species was I. histrix. There were more herbaria sheets of I. delilei than I. durieui and I. longissima because specimens were actively collected in different periods from the same locality (see Appendix). Nine out of 68 herbaria sheets were misidentified or lack the specific epithet. Correctly applied scientific name was given to seven out of nine herbaria sheets whereas the remaining two collections did not belong to Isoetes.
Isoetes histrix was present in 77 grids, I. durieui did it in nine, I. longissima in five and finally I. delilei in eight (Fig. 1).
DISCUSSION
Córdoba province is located in southern Spain, in the Andalusia region. It is an inland territory that, bioge-ographically, can be divided into two halves separated by the Guadalquivir River. The northern half belongs to Provincia Mediterránea Ibérica Occidental (Subprovincia Luso-Extremadurense, Sector Mariánico-Monchiquense). This area is a central sector of Sierra Morena range; mainly characterized by acid soils and rocks with quartzites, schists, and granites among other minerals although limestones outcrops can be found. The southern half mainly belongs to Provincia Bética (Sector Hispalense) (Fig. 1) (Rivas-Martínez c2005). It is made up of marls and limestones; the highest point of the province (1570 m) is found in the south within Sector Subbético. From this point of view, Isoetes species distribution is biased based on their ecological requirements. They generally grow in acid surfaces; therefore, the southern half of the province is not suitable excepting moist and sandy areas. In contrast, the northern half is mostly adequate habitat for this genus. All the species need moist or flooding zones; I. histrix can be found in less humid pasturelands nonetheless. In moister places it can be found together with I. durieui like in stream riverbanks (López Tirado et al. 2015). Isoetes histrix is also present in some of the grids of I. longissima and I. delilei. In this case, I. histrix do not share the same habitat, as always is found outside of flooded areas.
The higher abundance of I. histrix in the centre of the province (Fig. 1) is explained by a greater sampling in the surroundings of Córdoba town. This result can be of interest to understand the commonness of this species, which could be also found in most of the northern half grids. By contrast, Triano (c2010) excludes I. histrix from sector Subbético. Thus, its distribution in the southern half must be reduced to some grids of Guadalcázar municipality. Scattered and scarce localities of I. durieui were found. After almost a decade collecting Isoetes, it is clear that I. durieui is much less common than I. histrix (100 samples of I. histrix in opposition to three of I. durieui). Findings in other territories like Huelva province and Central Italy suggest the preference of I. durieui to rainier areas (López Tirado et al. 2015, López Tirado and Scoppola 2016). Isoetes longissima and I. delilei are restricted to annually flooded areas. They prefer shallow ponds in sandy soils and also being found more rarely in stream beds. Suitable areas in the southern half of Córdoba province are an exception, such as I. longissima in Puente Genil municipality (Devesa et al. 2018) and I. delilei in Guadalcázar municipality (López Tirado et al. 2016). By contrast, the northern half is better preserved and more suitable for these amphibious species.
Surface ornamentation of the megaspores was the main character to consider when identifying (Prada 1983), especially distinguishing between terrestrial species. Other traits like presence/absence of phyllopods or velum and habitat can also be significant. Nonetheless, phyllopods' presence without considering megaspores seems to be the common mistake to a wrong identification.
Isoetes specimens have not been traditionally and steadily collected, probably because they go unnoticed. This work updates the distribution of this genus in Córdoba province. It highlights the commonness of I. histrix, especially in comparison with the other terrestrial species I. durieui. Both of them cannot be correctly identified unless mature megaspores are checked. A total of 107 new localities provided by the author after a decade of sampling are recorded for three out of four threatened species. These new localities have been collected and they are still saved by the author for further analysis.
