Taxonomic review of the genus Pseudophallus Herald 1940 with an osteological study of Pseudophallus brasiliensis Dawson 1974 (Teleostei, Syngnathiformes, Syngnathidae)

Author(s)

Caio Isola Dallevo do Amaral Gomes

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2017-02-06

Examining board members

Mônica de Toledo Piza Ragazzo; Rodrigo Antunes Caires; Alessio Datovo da Silva

• Advisor: Mônica de Toledo Piza Ragazzo; George Mendes Taliaferro Mattox

Abstract

This work is divided in a taxonomic review of the genus Pseudophallus Herald 1940 and an osteological study of P. brasiliensis. Pseudophallus was described based on two species occurring on the coastal drainages of the Pacific Ocean in the new world (P. starskii and P. elcapitanensis) and later, an additional species from the coastal drainages of the Atlantic Ocean, P. mindii, with a distribution ranging until recently from the Brazilian state of São Paulo, to Belize in Central America, including the Caribbean islands. In 1974 a new species, P. brasiliensis, was described based on specimens collected in the Tocantins River with lower meristic counts than the Central American specimens and the ones from the rest of the Brazilian territory. Besides that, the Brazilian specimens presented a decreasing clinal variation in a South-to-North direction in some meristic counts. In 1982 this species was synonymized with P. mindii due to the fact that specimens collected in other localities presented meristic counts similar to those collected in the Tocantins River, indicating that these lower counts were due to an intraspecific variation along the distribution of P. mindii. In order to investigate this intraspecific variation in P. mindii, a taxonomic review was proposed which became a taxonomic review of the genus Pseudophallus. In total 443 specimens, including type material, of all the species of Pseudophallus from along their entire distribution on the Atlantic and Pacific drainages had their meristic and morphometric characters studied. Five species are recognized: P. elcapitanensis and P. starksii from the Pacific drainages, P. mindii and P. brasiliensis from the Atlantic drainages, revalidating P. brasiliensis, and a new species endemic of the Lake Izabal, in Guatemala. Those species were redefined and redescribed herein, with some comments on their taxonomy and biogeography. On the second part of this study, an exploratory study on the osteology of P. brasiliensis was conducted, with the purpose of getting familiar with the osteology of the Syngnathidae and to address nomenclatural questions of their anatomy. The Syngnathidae are represented by different species of pipefishes, seahorses and seadragons, with a great array of characteristics that make this group easily recognizable such as the body armor, edentulous jaws, absence of pelvic fins and intermuscular bones, gill opening reduced to a pore on the opercular membrane and mainly by the fact that the males carry the eggs in a breeding pouch. Although this group is so peculiar and morphologically distinct, osteological studies are rare and focused mainly on the seahorses (genus Hippocampus) and there are no phylogenetic studies based on morphological characters. In this study, it was possible to gather information about the osteology of P. brasiliensis that allowed comparing and discussing morphological questions that are being debated along the years in different studies available on the literature, such as the existence of the metapterygoid, and branchial arch and pectoral girdle arrangement. The osteology of P. brasiliensis was conducted taking in consideration these questions in order to create a basis for future anatomical and phylogenetical studies in this group. (AU)

• FAPESP's process: 13/19979-7 - Taxonomic revision of the pipefishes Pseudophallus mindii (Meek & Hildebrand 1923) and P. brasiliensis (Dawson 1974), with an osteological study of P. mindii in the osteological context (Teleostei: Gasterosteiformes: Syngnathidae)
• Grantee: Caio Isola Dallevo do Amaral Gomes
• Support Opportunities: Scholarships in Brazil - Master