NEW ACALYPTRATE FLIES — WHEELER 313 



relationship with the Trigonometopidae would seem to be a possibil- 

 ity, while on the basis of general morphological features the Clusiodi- 

 dae (Clusiidae) or the Anthomyzidae are suggested. Since some 

 dipterists consider that the Clusiodidae-Opomyzidae-Anthomyzidae 

 form a related group, the fact that Latheticomyia shows similarities 

 to both the clusiids and anthomyzids may be significant. 



Trigonometopidae: On superficial examination Latheticomyia 

 beai*s a certain likeness to Trigonometopus, which has, in the past, been 

 variously referred to the Lauxaniidae, Otitidae, Sciomyzidae, and 

 Clusiodidae. In Trigonometopus, however, vibnssae are absent, the 

 subcosta is complete and ends independently in the costa, there are 

 no visible costal breaks, the presutural bristle is absent, and the 

 mesopleura always has at least one bristle. None of the described 

 species has a striking body color pattern as in our flies, and most 

 have highly marked \vings. In actual fact, therefore, there seems to 

 be little phylogenetic relationship between the two. 



Anthomyzidae: Latheticomyia bears some resemblance to species of 

 Anthomyza, but the resemblances are not very compelling. The 

 an-angemeut of orbital bristles is similar, the facial structure, vibrissa, 

 oral hairs, bare mesopleura, and distal costal break are all rather 

 alike. In Anthomyza, however, there are no presutm-al dorsocentrals, 

 there are never more than four scuteUars, the scutellar disc is always 

 bare, the ocellars are parallel and arise outside the ocellar triangle, 

 the antennae are not at all porrcct, the arista is basal, a humeral 

 weakening of the costa is not evident, and the first femur nearly 

 always beai-s a stout thomlike spine. Since there are still other 

 dissimilar features, it does not seem likely that Latheticomyia shoidd 

 be considered as an aberrant anthomyzid. 



Clusiodidae (Clusiidae): One of the most remarkable features 

 of the clusiids is the great divei-sity in chaetotaxy, a fact which makes 

 any characterization of the family most chfficult. Thus Latheti- 

 comyia might possibly be forced into this family on the gi-ounds that 

 still greater diversity in bristle patterns is not too unexpected. 



Many features of Latheticomyia are to be found somewhere among 

 the clusiids: the arista is essentially clusiidiike, the arrangement of 

 orbitals occurs in Acartophthalmus, six strong scutellar bristles are 

 present in some species of Clusia and Clusiodes, presutural dorso- 

 centrals occur in some species of Clusiodes, and a humeral costal 

 break is present in Acartophthalmus while a distal costal break is 

 characteristic of the other genera. In its gi-oss appearance Latheti- 

 comyia beare only a weak resemblance to any clusiid; however, 

 Acartophthalmus, long considered a clusiid, also beare little resemblance 

 to other members of the family. 



