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

publication ID 10.11646/zootaxa.991.1.1

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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 View FIGURE 7 ; 8A,B View FIGURE 8 ). A scabrous development is exceptionally absent in A. bocainae   ( Fig. 6A,B View FIGURE 6 ), and both the lateral protuberance and scabrous cuticle are absent in A. truncata   ( Fig. 26A,B View FIGURE 26 ). Species in the sanctipauli   Group also have the apex of tergum X longitudinally narrowed and developed into a crest­like process ( Figs. 7A View FIGURE 7 , 11A View FIGURE 11 ). Many of the species also have paired longitudinal, serrate ridges on tergum X ( Figs. 7A,B View FIGURE 7 ; 17B View FIGURE 17 ), 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 View FIGURE 5 ; 16A,C View FIGURE 16 ). 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 View FIGURE 5 ; 7A,B View FIGURE 7 , 8A,B View FIGURE 8 ). A species less confidently placed in this group is Alterosa truncata   ( Fig. 26 View FIGURE 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 View FIGURE 10 ; 18A,B View FIGURE 18 ). Both species also have a small number of large phallic spines ( Figs. 10D View FIGURE 10 , 18D View FIGURE 18 ). 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 View FIGURE 9 ; 19A,B View FIGURE 19 ; 22A,B View FIGURE 22 ). 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 View FIGURE 9 ; 22A,C View FIGURE 22 ), the structure of the intermediate appendages, which are similarly spine­like in all of the species ( Figs. 9A,B View FIGURE 9 ; 13A,B View FIGURE 13 ), and the overall shape of segment IX ( Figs. 9A View FIGURE 9 , 13A View FIGURE 13 , 19A View FIGURE 19 ). 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 View FIGURE 12 ; 22A,B View FIGURE 22 ).

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 View FIGURE 15 ; 21A,B View FIGURE 21 ) 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 View FIGURE 15 , 21B View FIGURE 21 ). 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 View FIGURE 15 , 21C View FIGURE 21 ). Armature in the phallic apparatus is absent in A. holzenthali   ( Fig. 15D View FIGURE 15 ) and reduced in A. paprockii   ( Fig. 21D View FIGURE 21 ). 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 View FIGURE 14 , 20A View FIGURE 20 ), similar preanal appendages, each with its apex concave and bearing a stout spine ( Figs. 14A,B View FIGURE 14 ; 20A,B View FIGURE 20 ), similar concavely cupped bases to tergum X ( Figs. 14A View FIGURE 14 , 20A View FIGURE 20 ), and similarly shaped inferior appendages, with the second articles much shorter than the first ( Figs. 14A,C View FIGURE 14 ; 20A,C View FIGURE 20 ). 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 View FIGURE 20 ; 25A,B View FIGURE 25 ). 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 View FIGURE 24 , 25A View FIGURE 25 ), a similarity of the inferior appendages, with the second article shorter than the first and widened apically ( Figs. 24A,C View FIGURE 24 ; 25A,C View FIGURE 25 ), and the form of the intermediate appendages, which are very short and rounded in both species ( Figs. 24A,B View FIGURE 24 ; 25A,B View FIGURE 25 ). The placement of both Alterosa schadrackorum   and A. tripuiensis   within the guapimirim   Group is admittedly speculative.