Akko Birdsong and Robins

James L. Van Tassell & Carole C. Baldwin, 2004, A review of the gobiid genus Akko (Teleostei: Gobiidae) with description of a new species., Zootaxa 462, pp. 1-15 : 1-2

[[ Akko Birdsong and Robins ]]

Introduction

Amblyopus brevis was described by Günther (1864) from a single specimen collected along the Pacific coast of Panama. Two additional specimens were later obtained from stomach contents of a Centropomus and added to the collection at the British Museum. Günther (1869) placed A. brevis in the subgenus Tyntlastes based on its dentition (teeth in a single series). Jordan and Eigenmann (1886[1887]) elevated Tyntlastes to a genus and assigned to it the same species that comprised Günther ’s subgenus ( A. brevis and A. sagitta ). When Palmer (1952) reviewed the genus Gobioides , he created two subgenera: Gobioides , with 25-26 vertebrae and 14-16 anal-fin rays, and Tyntlastes , with 31 vertebrae and 19 anal-fin rays. He placed A. brevis in Gobioides based on its vertebral count of 26 (an incorrect count) and anal-fin count of 15.

Murdy (1998) reviewed Gobioides and noted that Amblyopus brevis Guenther does not belong in Gobioides based on its dorsal pterygiophore pattern of 3-221110 and a vertebral count of 11+16 (not 26 as given by Palmer [1952]). Those characters would place it in the “ Gobiosoma ” or “ Microgobius ” groups of the Gobiosomatini and thus part of the Gobiinae (sensu Pezold, 1993).

Birdsong and Robins (1995) erected Akko for a new species, A. dionaea [1] , from off Brazil. Akko dionaea has a dorsal pterygiophore pattern of 3-221110, 11+16 vertebrae, and a distinctive sensory papillae pattern in which horizontal row b is elongate, extending anteriorly to a vertical through the middle of the eye; dorsal row n is elongate, the left and right elements approaching or meeting at the dorsal midline; and rows x1 and x2 are continuous. Birdsong and Robins (1995) placed the genus in the Gobiosomatini but did not comment further on its relationships within the tribe because of the large number of osteological autapomorphies it possesses.

Fish collections made during a Smithsonian Institution cruise aboard the R/V Uracca to the Darien province of Panama in 2000 resulted in several specimens initially identified as Gobioides brevis . A Smithsonian expedition to El Salvador in 2002 resulted in 144 additional specimens. This species has a dorsal pterygiophore pattern of 3-221110, 11 precaudal and 16 caudal vertebrae, and the distinct papillae pattern of and most of the osteological autapomorphies present in Akko dionaea . Several specimens were sent to the British Museum where Anthony Gill confirmed that our specimens match those of the holotype of Amblyopus brevis . We therefore take the opportunity to redescribe Amblyopus brevis based on the new material and place it in the genus Akko , thus extending the range of Akko from the Atlantic to the eastern Pacific Ocean.

In addition, a previously undescribed gobiid species obtained during the El Salvador expedition appears to represent a new species of Akko . This species, which is larger than A. brevis , found in shallower waters (7-9 meters as opposed to 15-25 meters for A. brevis ), and separable from A. brevis on the basis of numbers of lateral-line scales, vertebrae, dorsal- and anal-fin rays, and pigment pattern, is described herein.

[1] Birdsong and Robins (1995) spelled the name of their new species “dionea” in the abstract but “dionaea ” in all other places in the paper. The species was named after the plant genus Dionaea. We conclude that “dionea” is a misspelling.