Alterosa, Blahnik Table Of Contents, 2005

Blahnik Table Of Contents, Roger J., 2005, Alterosa, a new caddisfly genus from Brazil (Trichoptera: Philopotamidae), Zootaxa 991 (1), pp. 1-60 : 56-57

Relationships within Alterosa

Characters useful for defining species relationships within Alterosa are primarily those of the male genitalia. Character polarity can be assessed most directly for those characters where the assumption of evolutionary progression from simple and generalized to complex and specialized can be applied. Species sharing what are implied to be derived character states are considered related. They are discussed below as five informally recognized species groups.

The sanctipauli Group includes those taxa with a rounded basal protuberance on tergum X on which the cuticle is scabrously developed ( Figs. 7A,B; 8A,B). A scabrous development is exceptionally absent in A. bocainae ( Fig. 6A,B), and both the lateral protuberance and scabrous cuticle are absent in A. truncata ( Fig. 26A,B). Species in the sanctipauli Group also have the apex of tergum X longitudinally narrowed and developed into a crest­like process ( Figs. 7A, 11A). Many of the species also have paired longitudinal, serrate ridges on tergum X ( Figs. 7A,B; 17B), although this character is not consistently present among all species. A possibly plesiomorphic character similarity is the shape of the inferior appendages, which are elongate, linear ( Figs. 5A,C; 16A,C). Species placed here with confidence include: Alterosa beckeri , A. bocainae , A. boraceiae , A. caparaonensis , A. fimbriata , A. intervales , A. itatiaiae , and A. sanctipauli . Of these, A. caparaonensis , A. beckeri , and A. boraceiae all have the intermediate appendages branched basally ( Figs. 5A,B; 7A,B, 8A,B). A species less confidently placed in this group is Alterosa truncata ( Fig. 26), without a basal scabrous protuberance on tergum X and with modified apices to the inferior appendages, but having paired longitudinal, serrate ridges on tergum X and also a tergum X with an apical crest­like development. Both of these latter characters are found within the sanctipauli Group and suggest the probable placement of A. truncata within this group.

Two species that have a general similarity to the sanctipauli Group include Alterosa falcata and A. jordaensis . These species greatly resemble each other in the peculiar development of their intermediate appendages, which are arched and curved apically and comparatively unarmed ( Figs. 10A,B; 18A,B). Both species also have a small number of large phallic spines ( Figs. 10D, 18D). They, however, lack the defining characters of the above group, as well as apomorphic characters that would place them in or near some other group. I have separated these two species as the falcata Group.

Another well­defined group is the marinonii Group including: Alterosa escova , A. flinti , A. fluminensis , A. marinonii , and A. sanctaeteresae . A defining character for the group includes the greatly modified and enlarged preanal appendages, which are widened basally and armed with stout, modified setae ( Figs. 9A,B; 19A,B; 22A,B). Character sim­ ilarities include the shape and structure of the inferior appendages, which have their basal segments bulbously rounded and their apical segments widened, each possessing a large pad of apicomesal setae ( Figs. 9A,C; 22A,C), the structure of the intermediate appendages, which are similarly spine­like in all of the species ( Figs. 9A,B; 13A,B), and the overall shape of segment IX ( Figs. 9A, 13A, 19A). Two species, A. flinti and A. sanctaeteresae , have an elongate lateral branch from the intermediate appendage that terminates with a brush of setae ( Figs. 12A,B; 22A,B).

A pair of superficially dissimilar species that nevertheless share some apomorphic character similarities include Alterosa holzenthali and A. paprockii . These are referred to here as the holzenthali Group. Both species have the posterolateral margin of tergum IX extending shelf­like over the base of tergum X ( Figs. 15A,B; 21A,B) and both also have very narrow, pencil­like intermediate appendages closely apposed to the lateral margin of tergum X, each with a spine­like apical seta ( Figs. 15B, 21B). The two species also have similarly developed inferior appendages, with the second article longer than the first and somewhat flattened on the mesal surface ( Figs. 15C, 21C). Armature in the phallic apparatus is absent in A. holzenthali ( Fig. 15D) and reduced in A. paprockii ( Fig. 21D). While they are similar to each other, there are no obvious characters for placing these species within or near one of the other species groups.

The guapimirim Group is more heterogeneous than the other groups recognized above and it is possible that it may not prove to be monophyletic. I have place here four species, A. guapimirim , A. orgaosensis , A. schadrackorum , and A. tripuiensis . The first two are very similar and are clearly closely related. Both have a similarly developed, bulbously enlarged tergum X ( Figs. 14A, 20A), similar preanal appendages, each with its apex concave and bearing a stout spine ( Figs. 14A,B; 20A,B), similar concavely cupped bases to tergum X ( Figs. 14A, 20A), and similarly shaped inferior appendages, with the second articles much shorter than the first ( Figs. 14A,C; 20A,C). A relationship of these species to A. tripuiensis is suggested by the development of the base of tergum IX, which is similarly laterally compressed and extends over the base of tergum X ( Figs. 20A,B; 25A,B). General similarities of A. schadrackorum to A. tripuiensis suggested its probable placement in this group, as for instance an overall similarity of the shape of segment IX ( Figs. 24A, 25A), a similarity of the inferior appendages, with the second article shorter than the first and widened apically ( Figs. 24A,C; 25A,C), and the form of the intermediate appendages, which are very short and rounded in both species ( Figs. 24A,B; 25A,B). The placement of both Alterosa schadrackorum and A. tripuiensis within the guapimirim Group is admittedly speculative.