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The Laboratorio di Biologia Sotterranea di Verona, attended the XIVth International Symposium of Biospeleology organized by the Societe International de Biospeologie in Makarska (Croatia) since 19 to 26 September 1999.
The Laboratorio di Biologia Sotterranea di Verona presented the first results of a research on the largest cavernicolous trechinae in the world: Italaphaenops dimaioi, living in the caves of the Lessini Mountains, near Verona.
Abstract of the poster presented to the XIVth International Symposium of Biospeleology.
New observations on the behaviour of Italaphaenops dimaioi (Coleoptera, Trechinae)
Caoduro Gianfranco
Laboratorio di Biologia Sotterranea di Verona, G.A.S.V. - Verona, Italy.
Distribution
Italaphaenops dimaioi Ghidini 1964 is one of the most interesting cavernicolous insects of italian fauna, in particular for its size, the largest troglobitic Trechinae. It is endemic of the caves of the Alti Lessini Veronesi and was collected the first time in 1963 in the Spluga della Preta at 510 m of depth. It is very rare and many insect collectors visit frequently the caves where it is often collected using destructive methods. After last investigations the distribution area appears larger and include the following caves : 1) Spluga della Preta 1 V/VR; 2) Spluga Carpene 396 V/VR; 3) Grotta dell’Arena 476 V/VR; 4) Abisso del Vajo dei Modi 3650 V/VR; 5) Grotta del Berclie 3 V/VR; 6) Grotta Regosse 161 V/VR; 7) Grotta Galleria Taioli 1121 V/VR; 8) Speluga di Spinei 374 V/VR; 9) Abisso di Bosco Scortigara 329 V.T.; 10) Cavità artif. Ponte Anguillara n. c.; 11) Cavità artif. Grotta dell’Arena n.c.
Breeding
Italaphaenops dimaioi does not breed easily in captivity. It is possible to get good results only with a careful and continuous maintenance of the terrarium. The author found a new system to create two different environments inside the terrarium. The substratum consists of two different materials. An area is covered with gravel (2-3 mm), 5 mm thick; whilst the rest is covered with loose silt coming from the cave where the animal was captured. The terrarium (20x12x7 cm) is positioned with a light slope with the gravel on the downward side to facilitate the accumulation of excess water.
Italaphaenops dimaioi requires frequent contact with water; it needs water to clean its buccal appendixes and legs. The terrarium is covered with transparent material; necessary ventilation holes (Æ 1 mm) should be more numerous in the upper part. In this way it is possible to create two micro-environments: on the downward side relatively moist with gravel and water, and on the upper side less moist with loose silt. The terrarium must be well-kept and clean; after one day it is necessary to remove the remains of food to avoid fermentations and development of fungi and bacteria.
Biological cycle
Until now there was no knowledge about the biological cycle of Italaphanops dimaioi. By analogy from what has been observed for other cavernicolous trechinae of the Pyrenees, Casale & Vigna Taglianti (1976) supposed that it was a predator with a crypto-metabolic cycle.
During the breeding of three specimens (1 male and 2 females) of Italaphaenops dimaioi the author succeeded in observing an ovodeposition. On the 8th of August 1999 a female laid an egg 2.05 mm long (Fig. 2) on loose silt. This may suggest that Italaphaenops does not have a crypto-metabolic cycle. On the basis of the size of the egg we can suggest the existence of different larval stages during which the larva feeds and grows.
Copulation
Each specimen is kept in a different terrarium because of the extreme aggressiveness displayed whenever two specimens have been put together in the same terrarium.
Using a particular partition film the author succeeded in keeping a male and a female in the same terrarium and to let them come in contact with each other temporarily. Copulation was observed twice for a duration of 30 and 190 seconds. Before copulation the female is very aggressive, and the male finds it difficult to climb over her without being attacked.
Feeding
A study on the food sources of Italaphaenops dimaioi is very difficult because of the extreme shortage of breeding specimens. In this first part of the investigation no test about food preferences was included. Necrophagous habits i. e. the predilection of Italaphaenops dimaioi to feed on dead organisms in captivity is confirmed.
Research Supported
by
Fondazione
Cassa di Risparmio di Verona
Federazione
Speleologica Veneta