Odonatologica 37(4): 305-315 December 1, 2008 Odonata diversity in a tropical dry forest of Mexico, 1. Sierra de Huautla, Morelos E. González-Soriano¹,F.A. Noguera ²,S. Zaragoza-Caballero¹, M.Á. Morales-Barrera¹,R. Ayala-Barajas²,A. Rodríguez-Palafox²† and E. Ramírez-García² 1 Departamento de Zoologla, Instituto de Biologla, Universidad Nacional Autonoma de Mexico, Avenida Universidad 3000, MX-04510 Ciudad Universitaria, D.F, Mexico 2 Estacion de BiologiaChamela, Instituto de Biologia, Universidad Nacional Autonoma de Mexico, Km. 59 Carretera Barra de Navidad-Puerto Vallarta,MX-48980 San Patricio,Jalisco Mexico t deceased Received October 19, 2007 / Reviewed and Accepted January, 21, 2008 A study of the fauna of Odonata of a tropical deciduous forest is presented. Col- lections were made monthlyduringa 1-yrperiod (Nov. 1995-Oct. 1996)during 5 days each month. A total of 2595 adult specimens were collected,belonging to 57 species, 33 genera and 8 families. Estimated richness value using the non-parametricestima- tor ICE was 76.28. INTRODUCTION This is of to the and of paper part a long-term project study diversity patterns distributionof the faunaof insects associated with the tropical dry forest (TDF) in Mexico (NOGUERA et al., 2002; ZARAGOZA et al„ 2003). The TDF is one of the most diverse ecosystems in Americaand also one of the it of the most endangered (JANZEN, 1988). In Mexico covers almost 8% coun- try’s surface and harbors a large number of endemic species (TOLEDO & OR- DONEZ, 1993; FLORES & GEREZ, 1994; CEBALLOS & GARCIA, 1995). This plant community extends in a more or less continuous fashion from Sonora to Chiapas states withother intrusionsin the Yucatan Peninsula and in some ar- eas of the Gulfof Mexico (PENNINGTON & SARUKHAn, 2005). Since 1990 only 27% of its surface has remained intact(TREJO & DIRZO, 2000). Odonata are predacious insects which do not depend directly upon plants, at least in the trophic level, as most of the other insects do. However, they use veg- etation in several other ways: e. g. as breeding sites for larvae (e. g. phytotelmata 306 E. Gonzalez-Soriano et. al and ground litter) (PAULSON, 2006) or for shelter, oviposition, roosting sites or habitat selection for adults (BUCHWALD, 1992; CORBET. 1999; PAULSON. 2006). Vegetation is also used for concealing adults from predators and as mat- ing areas and feeding perches (BUCHWALD, 1992). The study of the diversity and distribution of Odonata associated to the TDF is almost non-existent and only a few published works deal with this topic for Mexico (DUNKLE, 1976; GONZALEZ-SORIANO et al., 2004). MATERIAL AND METHODS STUDY - AREA The study area is located in a portion of the Sierra of Huautla Biosphere Re- o serve (SHBR), located in south central Morelos State, Mexico(l8"20T0”to 18°34'20”N and98 51'20” to 99°08T5”W) (DORADO, 1997). The climate is warm subhumid, type Awo"(w) (i') g according the Koeppen classification modified by GARCIA (1981). Average annual precipitationfor the period 824 with 80% of the rain from June Mean for 1981-1997 was mm, falling to September. temperature with maximum of 34.3°C and mini- the same periodwas 24.7°C, an average temperature an average of The site is included within the and the Amacuzac mum temperature I5,0°C (CNA. 2000). Atoyac river basins. The area is covered mostly by TDF although other plant associations are also found here (e.g. gallery forest, secondary vegetation and agriculture lands). Odonate collections were made at three sites. The first of these is located along the Quilamulariv- er (18°27’671”N, 99°02’475”W) near the facilities of the Center of Environmental Education and Research Sierra de Huautla the second made the river (CEAMISH), along a canyon by Ajuchitlan (18°27’065”N, 98°59’546”W)near the town of Ajuchitlan and the last one(Arroyo Los Idolos) at a secondary stream confluent with the Ajuchitlanriver near the entrance of the town. The first site (Qui- river due the of the lamula river) has water throughout the year specially down to presence Lorenzo Vazquez dam. The last two streams lack water duringthe dry season.Collections were made during five days of every month (between November 1995 and October 1996) and they werecarried out by the senior author and student de los in two persons; one (Ma. Angeles Morales), except September when collections were made only by the student. ANALYTICAL METHODS — The values of richness and abundance correspond to the number of species and individuals recorded. Diversity and evennesswereanalyzed with Shannon Index, using the natural and values obtained with the Pro logarithm, were program BioDiversity (McALEECE et al., 1999). individuals rich Considering that the observed number of any sample of from a species community underestimates the true number of species present, a non-parametric estimator of species richness was performed using data obtained duringthe year of the study to determine how close the richness value recorded was representative of the true local richness. The estimator used was ICE, an inci- dence-based estimator, because it best satisfied the requirements for an ideal species-richness estima- tor (CHAZDON et al., 1998). ICE estimator is based on species found in < 10 samplingunits and its formula is (COLWELL, 2006): S. , 0. mfr ,2 S. = S + + y ice freq q £ lce ice ice 10 where S is the number of species found in > 10samples, S is the number of species found in or f infr is numberof that in fewer samples; is the sample incidence coverage estimator. Q, the species occur 2 of only onesample and -y ice is the estimated coefficient of variation the Q,’s for infrequent species. The The collected estimates were calculated using Estimate S 6.0bl (COLWELL, 2006). species within each day were considered onesample unit (53 in total). Odonata diversity in tropical dry forest 307 to to For phenologyanalysis of the data, weconsidered the rainy season last from May November and the dry season to last from December to April. This was based on the occurrence of individual storm events totalinggreater then 15 mm, because the canopy intercepts smaller amounts almost completely(CERVANTES, 1988). RESULTS RICHNESS A totalof 2595 adult to 57 33 specimens were collected, belonging species, gen- values of the of the era and eight families. These represent 61% species, 82% gen- era and 89% of the families previously reported for the state of Morelos, Mexico (GARCIA, 1987; G0NZALEZ-S0RIAN0& NOVELO-GUTIERREZ, 1996, 2007; NOVELO, 1997). Libellulidaewith The familywith the greatest numberof species was 27 species (47% of the total), followed by Coenagrionidae with 16 (28%), Aeshnidaewith 7 (12%), Gomphidae with 3 (5%) and Calopterygidae, Lestidae, Platystictidae and Protoneuridaewith one each (2% each). Libellulidae was also the family with the greatest number of genera with 16 (48%) followed by Coenagrionidae and Aeshnidaewith 5 each (15% each), Gom- phidae with 3 (9%); Calopterygidae, Lestidae, Platystictidae and Protoneuridae with one each (the remaining 13%). diverse with followed Argia was the most genus 9 species (15.8%) by Enallagma, Erythrodiplax, Dythemis and Micrathyria with three species each (21%), Ischnu- and ra, Rhionaeschna, Gynacantha, Libellula, Macrothemis, Orthemis, Perithemis with two each The rest of the consisted of Tramea species (28.1%). (21) genera one species each (37%). Thus, 65% of the genera recorded were represented by two or fewer species. ESTIMATED RICHNESS. — The richness estimatedwas larger than the richness observed: 76.28 (SD ± 0.02) against 57 spe- cies. This may mean that we only recorded 75% of the true local richness. On the other hand, the species accu- mulation curve com- puted had began to reach the asymptote (Fig.l), which proba- bly indicates that the estimated value could Fig. 1. Observed (circle) and estimated (square)species accumulation be reflection of a true curves of Odonata fauna of Huautla, Morelos. 308 E. Gonzalez-Soriano et. at the estimatedrichness for this lo- cality. ABUNDANCE The distributionper species of 2595 adult specimens was hetero- few geneous; a species were very abundantbut most others were represented by one or a few indi- viduals(Fig. 2). The most abun- dant species was Argia tezpi with 443 individuals, followed by A. with with pulla 362, A. oenea 194, Hetaerina americana with 190, Telebasis salva with 151, Dythemis nigrescens with 119 and Protoneura cara with 109. All abundant species (excepting the libellulid D. nigrescens) are zygopterans. In contrast, 11 spe- cies were represented by one in- dividual and 17 by less than 10 individuals. Fig. 2. Rank-abundance pattern of the Odonata of Sierra de Huautla. DIVERSITY The valuecalculated with the Shannon Index the entire diversity over year was 3.04and the evenness index was 0.75. The diversity values by month varied, with the lowest valuerecorded in May (2.2) and the highest recorded in July (3.1). The lowest and highest values of the evenness index were recorded in April (0.755) and July (0.91) respectively (See Table 1) Table I Diversity and evenness indexes obtained monthly of the Odonata fauna from Huautla, Morelos Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Diversity 2.99 2.8 2.6 2.8 2.4 2.4 2.2 2.3 3.1 2.3 3.01 2.8 Evenness 0.84 0.85 0.82 0.87 0.79 0.75 0.78 0.76 0.91 0.88 0.85 0.89 Odonata diversity in tropical dry forest 309 Fig. 3. Pattern of species richness (circles) and abundance (squares) of Odonata of Sierra de Huaut la per month. PHENOLOGY The annual activity pattern showed that the richness reached the highest value in November (36), at the end of the rainy season and the lowest in May (17), at the end of the dry season, with a gradual and nonconstant decrement between the highest and lowest value(Fig.