Psocoptera (Insecta: Psocodea) from the National Natural Park Gorgona, Cauca, Colombia

The Psocoptera fauna of Gorgona National Natural Park, Colombian pacific, consists of 75 species in 42 genera and 21 families. 1 730 specimens were collected in the period November 2007-June 2011. Five families, 20 genera and nine species are new records for Colombia, and two genera and ten species are new to science. The psocid fauna of the island constitutes an extension of the continental fauna. Rev. Biol. Trop. 62 (Suppl. 1): 243-256. Epub 2014 February 01.

Psocids (Psocodea: 'Psocoptera'), are small, neopterous, exopterygote insects, characterized by having filiform antennae, bulbous postclypeus, asymmetric mandibles, and maxillae with elongate, free laciniae; the wings are membranous, with simple venation, in most species placed roof-like over the dorsum; apterism and brachypterism are frequent, and the tarsi are 2-3 segmented in the adults and always 2 segmented in the nymphs.For general information on the biology of these insects, see Badonnel (1951), Lienhard (1998), Mockford (1993) and New (1987).For relationships within the order Psocodea, see Bess, Smith, Lienhard & Johnson (2006).They are essentially wild, free living insects that constitute part of the aerial plankton (Simberloff & Wilson, 1969), and represent a significant fraction of the biomass in temperate forests (Thornton, 1985); they are probably key organisms in the trophic network of many ecosystems, as they are prey of many vertebrates and invertebrates, and they are primary consumers, feeding on algae, lichens, mycelia that grow on foliage, tree trunks and rock surfaces, and occasionally on pollen grains (Lienhard, 1998).They are found in living and dead foliage, leaf litter, cortex of trees and shrubs, rock surfaces and human habitations (Mockford, in prep., García-Aldrete, 1990).
It is a diverse group, with more than 5 500 species, in more than 435 valid genera, and more than 40 families (García-Aldrete, 2006).They have been found all over the world, being particularly species rich in the tropics (García-Aldrete, 1988).In Colombia, only a few species have been recorded so far (87 species), but being a megadiverse country, we anticipate that its psocid richness will be comparable to the richness of other neotropical countries, although for most of them the inventory is rather incomplete (see García-Aldrete, 2008, for a list of Mexican Psocoptera, and García-Aldrete & Mockford, 2009, for a list of Brazilian Psocoptera).The Pacific islands of Gorgona and Gorgonilla presently constitute the National Natural Park (NNP) Gorgona, a protected area in Colombia that was strongly altered anthropogenically in the past, on account of the establishment there of a high security prison, cancelled in 1984.It constitutes a representative area of highly humid tropical forest in the biogeographic Colombian Chocó, quite diverse biologically.The arthropods in general have been little studied, and in this work we present a preliminary list of Psocoptera, with information on the habitats where they have been found, resulting from field work in the NNP Gorgona, between 2007 and 2011.
The specimens were taken directly from the substrate, by beating vegetation, by sweeping with a soft brush (3-4 inches wide), tree trunks and rock surfaces, and by sifting leaf litter; the specimens were taken in beating cloths of about 60x60cm, or in plastic, rectangular trays (25x40x10cm), and transferred to containers with 80% ethyl alcohol, utilizing mouth aspirators.Malaise, Shannon and led light traps were also utilized, placing the latter near the canopy, at heights of 15 and 20m.For the identification, it was necessary to dissect the specimens and mount their parts permanently on slides in Canada balsam (see García-Aldrete, 1990 and González-Obando, García-Aldrete & Carrejo, 2011).Table 1 lists the coordinates, altitudes and abbreviations for the collecting localities (Fig. 1) noted for each species.

RESULTS
1 730 specimens were taken, in which 75 species of Psocoptera are represented, in 42 genera and 21 families; six families, 21 genera and 20 species constitute new records for the Colombian fauna, at least ten species are new to science, three of which have just been recently described (García-Aldrete, Gonzalez & Sarria-S 2011).The most diverse family is Psocidae, with eight genera and 18 species, followed by Lepidopsocidae, with five genera and six species; the most speciose genera are Ectopsocus (eight species), Valenzuela (six species), and Blastopsocus (five species); six genera are represented by two species, and 25 genera are represented by one species.Table 2 summarizes densities and the different habitats where the species were collected.

DISCUSSION
The distribution of the abundance of the species found follows the usual pattern of a few species represented by many individuals, many species represented by one or few individuals, and a middle group of species with intermediate values (Table 3).Given the close proximity of Gorgona Island to the mainland, separated by only 35km, it is not surprising that the species richness be quite high; in comparison with other islands in the Mexican Pacific is meaningful, as it shows that, according to the theory of island biogeography (MacArthur & Wilson, 1967), small islands have fewer species than large islands, and distant islands have fewer species than close islands to the mainland (Table 4, García-Aldrete, 1986; García Aldrete, Cadena-Carrión & Cervantes-Peredo, 1992); unfortunately, we still do not have a good psocid census of the mainland near the NNP Gorgona, but the evidence we have indicates that, most probably, the level of endemism is low, so far with only Lepolepis sp., Goja sp., the three species of Loneura, the genus ca.Kaestneriella, and the new genus of Psocidae as probable endemics to NNP Gorgona, so it would seem that the island fauna is an extension of the continental fauna.An interesting feature of the fauna, comparing it with the other Pacific islands, is that only one species, the widely distributed Pseudocaecilius citricola (Ashmead), is shared among the five islands (Table 4).
Of particular interest are the records of Lepidopsocus pretiosus Banks and Nepticulomima hoesemanni Enderlein in the NNP Gorgona; the former was known from Guam, Micronesia, Christmas Island, Indonesia, Melanesia and Polynesia, and the latter was known from several African countries and from Christmas Island, and was recently recorded at the Waorani Ethnic Reserve, in Napo, Ecuador (Lienhard & Smithers, 2002;García-Aldrete, 2001).
The most abundant species were Echmepteryx madagascariensis (Kolbe), E. falco Badonnel, and Heterocaecilius sp., that together, account for 35.6% of the specimens collected.The first two are pantropical, and are among the first colonizers of secondary vegetation in the Pacific (Thornton, 1985), which may explain their presence and abundance in the NNP Gorgona.They were found throughout the island, but were most abundant at the beaches and near the small town, where the density of coconut palms is high; this agrees with the finding of Thornton et al. (1988), on Java, Indonesia, where they found lepidopsocids mostly on dead palm fronds.
The diversity of Psocoptera in the biogeographic Chocó is unknown, but upon comparing the genera found in the NNP Gorgona, with those recorded in Colombia, we found an index of faunistic similarity of 42%, meaningful but preliminary, and likely to go down, as the Colombian fauna gets to be better known.Also, upon comparing Fisher's α diversity index for the psocids of the NNP Gorgona, with the values for other areas (Table 5), such as Fortuna, Panama, and the Krakatau archipelago, with areas of 195 and 25.4Km 2 respectively, we found a relatively high value, given the small area of the NNP Gorgona (13.8Km ).
In Colombia, 21 families, 42 genera and 87 species have been recorded (  In summary, the psocid fauna of the NNP Gorgona requires further study, to identify to species level, and to verify which of the species are undescribed.The rich psocid fauna of the NNP Gorgona, as compared to the psocid fauna of other Pacific islands, particularly the Mexican Tres Marías and Revillagigedo archipelagos, and the closeness to the continent, indicates that its fauna is an extension of the continental fauna.To ascertain the point above requires a psocid survey of the continental fauna in the area closest to the NNP Gorgona.

TABLE 1
Keys and coordinates of collecting localities in the NNP Gorgona

TABLE 4
Number of species of Psocoptera (S), area (Km 2 ), and distance to mainland (DM, Km) in five Pacific islands thanked for their invaluable help and logistic support during field work in Gorgona Island.RESUMENLa fauna de Psocoptera (Psocodea) del Parque Nacional Natural Gorgona, consiste de 75 especies en 42 géneros y 21 familias.1 730 especimenes fueron recolectados en el periodo entre noviembre de 2007 y junio de 2011.Cinco familias, 20 géneros y nueve especies son nuevos registros para Colombia, y dos géneros y diez especies son nuevos para la ciencia.La fauna de Psocoptera de la isla constituye una extensión de la fauna continental.Costa del Pacífico, Colombia, los parques nacionales naturales, la lista de especies.