Preliminary report on the water mites (Hydrachnidia, Prostigmata) of ALAS-IV

Tom Goldschmidt

University of Karlsruhe, Zoological Institute I, Kornblumenstraße 13, D – 76128 Karlsruhe, Germany, Tel. +49-721-608 8358, Fax. +49-721-608 8234, email: dc30@rz.uni-karlsruhe.de

dc30@rz.uni-karlsruhe.de

Introduction

Until now 77 genera of water mites are known from Costa Rica, with 134 species described or reported from the country (Cook 1980, Springer & Gerecke 1992, Goldschmidt & Gerecke in press, Goldschmidt submitted). Within Latin America, the water mite fauna of Costa Rica can be considered as one of the ‘better known’, nevertheless, 3/4 of the fauna is probably still unknown. A total number of about 500 water mite species can be expected in Costa Rica, approximately 5500 species are estimated for the whole Neotropic (Goldschmidt 2002).

During ALAS-IV (8. – 13. April 2003), 38 water mite samples have been collected at 14 sites in the surroundings of the El Ceibo station (500m site). Samples have been taken mainly from rivers and streams, but some springs and swamps have also been considered.

Results of water mite collections near the OTS-station of La Selva in 1997 and 2003, as well as in the Laguna Barva in 1996 are also included in this report.

Methods

Water mites were collected with a hand net with a mesh-size of 250µm. Different habitats such as riffles, pools, moss carpets, etc. were sampled separately at each site. Therefore the substratum has been disturbed by hand, stones were turned and detritus together with the benthic invertebrates were washed downstream into the net. After being washed through a course sieve (mesh-size 2-3mm), the samples were transferred into a white Frisbee and in most cases revised directly in the field. Mites were picked up with tweezers and eye-droppers and fixed in Koenike’s solution (glycerine (10 parts) : acetic acid (3 parts) : water (6 parts)). Habitat characteristics such as water-temperature, pH, conductivity, stream current, stream size, shading, micro-habitats, surrounding vegetation, etc. have been registered.

Results

At El Ceibo most samples (22) have been taken in small streams (1-5m width), 7 sites of this type have been considered; 9 samples have been taken in 2 mid-size streams (5-10m width); 3 samples in 2 spring brooks (<1m width); 2 samples in 2 rheopsammocrene springs and 1 sample in a swamp.

At these 14 sampling sites in the surroundings of El Ceibo, 882 water mites have been collected, representing 37 genera and 16 families (Tab. 1). The dominant family are the Torrenticolidae, mainly represented by the genera Torrenticola (295 specimens, 33% of all water mites collected) and Monatractides (133 specimens, 15% of all water mites).

Tab. 1: Water mite families and genera collected at El Ceibo, 8. – 14 April 2003.

		specimens	samples
Limnocharidae	Rhyncholimnochares	1	1
Hydryphantidae	Protzia	5	3
Hydrodromidae	Hydrodroma	7	4
Rhynchohydracaridae	Clathrosperchon	4	4
	Rhynchohydracarus	2	1
	Santiagocarinae (gen. nov.)	1	1
Sperchontidae	Sperchon	18	6
Lebertiidae	Lebertia	1	1
Oxidae	Frontipoda	30	3
Torrenticolidae	Monatractides	133	22
	Neoatractides	33	17
	Torrenticola	295	27
	Pseudotorrenticola	15	6
Limnesiidae	Limnesia	31	14
	Neotorrenticola	16	4
	Neotyrrellia	5	1
	Protolimnesia (Protolimnesella)	2	2
Omartacaridae	Omartacarus	3	2
Hygrobatidae	Atractidella	37	7
	Atractides	59	18
	Corticacarus	13	5
	Hygrobates	86	15
	Paraschizobates	11	7
Unionicolidae	Koenikea	22	6
	Neumania	3	3
	Unionicola	1	1
Aturidae	Albia	3	3
	Aturus	1	1
	Axonopsalbia	2	2
	Axonopsella	1	1
	Axonopsis	1	1
	Diamphidaxona	4	3
	Frontipodopsis	7	7
Mideopsidae	Mideopsis	15	6
Krendowskiidae	Geayia	9	3
Arrenuridae	Arrenurus	2	2
	Stygarrenurus	3	1
Total		882	38

56% of all specimens were collected in the strong current, in riffle zones and moss carpets in the main current of streams; 21% in the gravel zones and root mats of terrestrial vegetation closer to the banks of rivers and streams in weaker current; 11% in calm pools at the banks or behind large rocks in streams. More than 75% of all genera have been found in the strong current, but even as the number of individuals in the pool samples has been low, still 49% of all genera have been found there, some representatives of the family Aturidae were only found in pools.

In the splash-zone at large rocks in the Río Peje, an interesting hygropetric fauna has been found, consisting of terrestrial mites belonging to the Trombidiformes, beetles of the family Dryopidae, several Diptera, Trichoptera and also some very interesting aquatic mites of the genera Neotorrenticola and Neotyrrellia (Goldschmidt et al. 1999, submitted).

In water bodies around the OTS-station of La Selva, 25 samples have been taken at 14 sites during a first stay in 1997 (28. February – 3. March) and the days before going to El Ceibo in 2003 (5. / 6. April). The main habitats considered have also been small streams (13 samples at 7 sites), followed by mid-size streams (8 samples, 3 sites), spring brooks (2 samples, 2 sites), a large river (1 sample, 1 site) and a swamp (1 sample, 1 site). 827 water mite specimens representing 28 genera in 13 families have been found in the surroundings of La Selva (Tab. 2). The dominance of the genus Limnesia (176 specimens, 21% of all water mites collected) is mainly caused by one sample containing 157 specimens (see appendix).

Tab. 2: Water mite families and genera collected at La Selva, 1997 and 2003.

		specimens	samples
Limnocharidae	Rhyncholimnochares	17	2
Hydryphantidae	Protzia	2	1
Hydrodromidae	Hydrodroma	1	1
Sperchontidae	Sperchon	135	10
Lebertiidae	Lebertia	4	3
Torrenticolidae	Monatractides	45	5
	Neoatractides	6	4
	Torrenticola	109	12
	Pseudotorrenticola	4	2
Limnesiidae	Limnesia	176	5
	Neomamersa	3	2
	Neotorrenticola	3	2
	Neotyrrellia	3	2
Hygrobatidae	Atractidella	44	9
	Atractides	108	14
	Corticacarus	38	8
	Hygrobates	67	17
	Stylohygrobates	1	1
	Paraschizobates	1	1

Unionicolidae	Koenikea	8	4
	Neumania	9	3
Aturidae	Albia	2	1
	Neoaturus	1	1
	Frontipodopsis	2	1
Mideopsidae	Mideopsis	10	3
Hungarohydracaridae	Cubanohydracarus	1	1
Arrenuridae	Arrenurus	25	2
	Stygarrenurus	2	1
Total		827	25

In March 1996, a small sample of water mites has been taken in the Laguna Barva, yielding 11 specimens of the genus Limnesia.

Discussion

The samples taken at El Ceibo, in comparison with those from La Selva are showing a higher diversity. Within comparable samples, 24% more genera have been found at El Ceibo. The families Rhynchohydracaridae, Oxidae, Omartacaridae and Krendowskiidae have only been found at El Ceibo. Five Aturidae genera (all in low numbers) are restricted to the samples from El Ceibo. The rare family Hungarohydracaridae, present in one specimen in the samples from La Selva, has not been found at El Ceibo.

The dominance of the genera Torrenticola and Monatractides in streams at El Ceibo is typical for mountain streams in tropical and also temperate regions. In previous studies on Costarican water mites, representatives of the family Torrenticolidae have been found in more than 60% of all samples over a wide variety of habitat characteristics (Goldschmidt 2001). Taxonomic and ecological studies on the Torrenticolidae of Costa Rica are implemented at the moment.

The family Rhychohydracaridae, restricted to the El Ceibo samples, is very remarkable (even as found in only 7 specimens): The genus Clathrosperchon is known from several small to mid-sized streams in mountain regions in different parts of Costa Rica, mainly at an elevation of 500 to 1000m asl. The genus Rhynchohydracarus, described from Paraguay and Southern Brazil, and recently also found in Panama (Valdecasas 2001), until now in Costa Rica has only been known from two streams in the Monteverde area, at 1200m and 1400m asl (Goldschmidt 2001). Two specimens of this genus have been found in a small stream at El Ceibo. The subfamily Santiagocarinae has been described from Panama (Valdecasas 2001), an undescribed genus of this subfamily has been found in the Quebrada Lajas near El Ceibo.

The genus Omartacarus has an Australian-American distribution, until now the genus is known in only a few specimens from Central America. In Costa Rica 3 findings are known in Guanacaste, one at the San Ramon field station.

Within the samples taken at La Selva (apart from the differences to El Ceibo, mentioned above) the high abundance of the genus Sperchon is especially remarkable. In previous studies the genus has been found in a wide variety of stream habitats, but with a strong bias towards higher elevations above 1500m asl (Goldschmidt 2001). The main distribution of the genus Lebertia, also found in some specimens at La Selva, in Costa Rica is above 3000m asl (Goldschmidt 2001). In general several aspects of the water mite communities in the streams of La Selva resemble a mountain stream fauna, typical for much higher elevations. A general analysis of the ecology, especially the habitat binding of the water mite genera of Costa Rica is in preparation (Goldschmidt in prep.).

Remarks

The logistic preparation of the field trip has been excellent, still a topographic map of the site would have been helpful.

Acknowledgements

I’d like to thank the group of ALAS-collaborators who spent the week of 8. – 13. April 2003 at El Ceibo with me, for the great atmosphere and interesting discussions. I want to say special thanks to the ALAS-staff Maylin, Flor, Danilo and Ronald for all their great help and friendliness at El Ceibo and during the preparation of this field trip.

Literature

Cook, D.R. (1980): Studies on Neotropical water mites. Memoirs of the American Entomological Institute 31: 1-645.

Goldschmidt, T., G. Alberti & E.I. Meyer (1999): Presence of acetabula-like structures on the coxae of the neotropical water mite genus Neotyrrellia (Tyrrellinae, Limnesiidae, Prostigmata). In: Bruin, J., L.P.S. van der Geest & M.W. Sabelis (Eds.): Ecology and Evolution of the Acari. Kluwer Academic Publishers, Dordrecht, Boston, London: 491-497.

Goldschmidt, T. (2001): Die Wassermilbenfauna Costa Ricas (Hydrachnidia, Acari) – Systematik, Ökologie, Diversität und Zoogeographie. pp. 1-425. Dissertation, Westfälische Wilhelms-Universität Münster.

Goldschmidt, T. (2002): The Biodiversity of Neotropical Water Mites. In: Acarid Phylogeny and Evolution: Adaptation in Mites and Ticks. F. Bernini, R. Nannelli, G. Nuzzacis and E. de Lillo (eds.), Proceedings of the 4rd Symposium of the EURAAC 24-29 July 2000, Siena, Italy. pp. 91-99. Kluwer Academic Publishers. Dortrecht, Boston, London.

Goldschmidt, T. & Gerecke, R. (in press): Studies on hydryphantid water mites (Acari: Actinedida: Hydrachnidia) from Central and South America. Interational Journal of Acarology (West Bloomfield).

Goldschmidt, T. (submitted): Untersuchungen über Wassermilben der Familie Anisitsiellidae Koenike, 1910 aus der Neotropis (Acari, Actinedida, Hydrachnidia). Senkenbergiana Biologica

Goldschmidt, T. (submitted): Studies on neotropical Limnesiidae Thor, 1900.
Part I: Neomamersinae Lundblad, 1953.
Part II: Tyrrelliinae Koenike, 1910
Part III: Protolimnesiinae Viets, 1940

Goldschmidt (in prep.): Environmental parameters determinating the water mite communities in Costa Rican freshwater habitats.

Springer, M. & Gerecke, R. (1992): The male of Neotorrenticola plumipes Lundblad, 1953 (Acari, Actinedida, Limnesiidae) from Costa Rica. Studies on Neotropical Fauna and Environment 27 (4): 243 – 252.

Valdecasas (2001): A new subfamily of Rhynchohydracaridae (Acari, Hydrachnellae) from the island of Coiba (Panama) with descriptions of new taxa. Journal of Natural History 35: 1565-1574.

Appendix: Excel-sheet containing the raw data of the collections at La Selva and El Ceibo.