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The present study aims to fulfill the gap of taxonomic knowledge on Triphoridae from Brazil. We describe five new species (Isotriphora uncia sp. nov., Isotriphora leo sp. nov., Monophorus verecundus sp. nov., Sagenotriphora albocaput sp. nov., Similiphora lucida sp. nov.), report five species previously known only from the Caribbean and related areas (Cheirodonta dupliniana (Olsson, 1916), Eutriphora auffenbergi Rolán & Lee, 2008, Isotriphora tricingulata Rolán & Fernández-Garcés, 2015, Marshallora ostenta Rolán & Fernández-Garcés, 2008, Monophorus caracca (Dall, 1927) comb. nov.) and describe six morphotypes at the generic level (Isotriphora sp. 1, Marshallora sp. 1, Nanaphora sp. 1, Sagenotriphora sp. 1, Sagenotriphora sp. 2, Similiphora sp. 1). Remarks are made to some species previously recorded from Brazil, including the invalidation of records, problems of generic allocation and geographical range extensions. Maps of the geographical distribution are provided for the 65 currently recognized species of Triphoridae from Brazil. Of these, 31 species are endemic to Brazil and 58 inhabit the continental shelf vs only seven from the continental slope. A distinct geographical zone occurs in southeastern Brazil. A few species occur exclusively near the mouth of the Amazon River, whereas others inhabit a local biogenic reef, possibly serving as a biogeographical corridor that connects western Atlantic populations. Species of Isotriphora from Brazil are particularly common around oceanic islands, probably due to adopting intracapsular metamorphosis, which may have evolved in more than one evolutionary event.
The alpha-taxonomy of triphorids is still largely based on the study of the shell, and the scarcity of studies dealing with their anatomy is a result of the difficulty of sampling live animals and their very small size. Whereas radula and operculum are important structures in the taxonomy at the generic level, the jaw of triphorids has never been properly studied, being regarded as presenting a morphological homogeneity. The present research explored the basic anatomy (especially internal hard structures: operculum, jaw and radula) of 12 species from Brazil, distributed in 11 genera: Cheirodonta Marshall, 1983 (with a new generic allocation, Cheirodonta dupliniana (Olsson, 1916) comb. nov.), Cosmotriphora Olsson & Harbison, 1953, Iniforis Jousseaume, 1884, Latitriphora Marshall, 1983, Metaxia Monterosato, 1884, Monophorus Grillo, 1877, Nanaphora Laseron, 1958, Nototriphora Marshall, 1983, Sagenotriphora Marshall, 1983, Similiphora Bouchet, 1985 and Strobiligera Dall, 1924; in addition, the basic anatomy of the Caribbean species "Inella" harryleei Rolán & Fernández-Garcés, 2008 was analysed. Radular examination showed that the majority of species studied is properly allocated in their genera after comparisons in the literature with respective type species, albeit a few species are clearly in need of a new generic allocation. The jaw of triphorids is remarkably heterogeneous, displaying different patterns of scales and micro-pores between outer and inner sides.