118 THE entomologist's eecokd. 



we know that the American genus Xenodusa, which in that country 

 takes the place of our Lomechusa and Atemeles, belongs to the true ant 

 guests, and the species are fed and licked by their hosts. These facts 

 are likewise just as certain in the case of the just described Xenodusa 

 sharpi, Wasm., from Mexico, and the newly discovered A", caseyi, 

 Wasm., from Colorado, as if their intercourse with ants had been 

 closely observed for ten years. 



Lomechon alfaroi, which I described a little time ago, lives in 

 Costa Rica with a big ant, Pachecondyla aenescens, Myra, of the sub- 

 family Poneridae, which has a very powerful sting. The discoverer of 

 this guest, Herr Anastasio Alfaro wrote on the locality label " muerde 

 muy fiero " (it stings fiercely). It proved a real enigma to find a 

 systematic position for this interesting beetle. It did not appear to 

 belong to a quite new genus, yet none of the known families seemed 

 to own it. At first I thought it belonged to the EndonnjcJndae as the 

 shape of its body was somewhat like a Lycoperdina. This similarity, 

 however, was only a deception caused by the beetle's adaptive characters. 

 Its specific characters were hidden under them, as under a mask. 

 It necessitated an arithmetical operation to subtract the adaptive 

 characters from the appearance of the Lomechon to find the family 

 characters. I at last classed it in the SUphidae with a certain amount 

 of assurance, of which family it possessed the abdomen, underside and 

 legs, all the other characters were purely deceptive. Its apparent 

 similarity Avith the Endomychidae arose from the shape of the thorax 

 in connection with that of the abdomen. The thorax, however, 

 resembled more that of a very eccentric Lomechusa or Xenodusa, on 

 account of its broad shell-like shape and upward bent posterior angles. 

 The head was like that of a Lomechusa, and antennte those of a 

 Xenodusa. The peculiar shape of the thorax, head and antennfe were, 

 however, only adaptive characters, of biological, but not of systematic, 

 importance. This new creature from Costa Rica must be, like 

 Lomechusa, a true guest. It possesses big tufts of reddish-yellow hair, 

 which, however, are not placed, as in the Staphylimdae, on the sides of 

 the abdomen, as that part is completely covered by the elytra in 

 the SUphidae, but inside the upward bent posterior angles of the 

 thorax. On account of the bunches of tufts of hair which possess 

 so much biological importance, as well as its resemblance to a 

 Lomechusa, this new ant guest has received the generic name of 

 Loniecho7i. 



Another example of the biological value of adaptive characters was 

 given me lately by a Brazilian Staphylinid. This example is all the 

 more instructive, as it was not even marked " Found with ants." In 

 spite of this, it was easy to determine a priori, the name of its host. 

 Father Badariotti, Congr. Sales., sent one from Lorena (Staat St. 

 Paulo) a short time ago, in the same tube with some non-myrmeco- 

 philous beetles — a big broad species belonging to the svibfamily Quediini, 

 which possessed, as far as size and shape, some resemblance to our 

 hornet's gu.est, Velleius dilatatus. Its peculiar colour and hair-groAvths 

 struck me as suspicious as soon as I took it out of the tube and pinned 

 it. The brown red colour and the shaggy hair reminded me at once of 

 the big neo-tropical leaf-cutting ants of the Atta family [Oecodoma). I 

 took the lens and studied it closely. The femur and tibia Avere flat 

 and shaped like leaves, and the antennas short and pressed to the sides. 



