Acinocheirodon melanogramma Malabarba & Weitzman, 1999
pequira, piabinha, lambari (Brazil)
Acinocheirodon melanogramma is distributed in the São Francisco and Jequitinhonha River basins, Brazil (Malabarba & Weitzman, 1999; Malabarba, 2003).
Environment This species inhabits clear freshwater streams, in general with moderate current.
Feeding type Unknown. Feeding habit Unknown.
There is little information about the life history and behavior of Acinocheirodon melanograma. It is known that A. melanogramma is an inseminating species due to the observation of spermatozoa inside the ovary of females (Burns et al., 1997), however fertilized eggs and embryos were never observed. The males in a certain stage of maturation start to develop several sexually dimorphic features. Some of them are very common among the characids, like the presence of hooks in the pelvic- and anal-fin rays. Other differentiations are uniquely found in this species, like the presence of hooks on some of the caudal-fin rays associated with hypertrophied caudal tissue, in the shape of flaps (Malabarba & Weitzman, 1999).
Acinocheirodon melanogramma is diagnosed from all characids by the presence of one row of pedunculated teeth in the upper and lower jaws, presence of pseudotympanum, absent of humeral spot, lateral line completely perforated and the presence of hooks and hypertrophied tissue on the caudal fin.
The type locality is in the municipality of Bocaiúva, a small stream called Córrego Cachoeira, a tributary of the Jequitaí River, about 17°28'S, 44°02'W, São Francisco River drainage, Minas Gerais State, Brazil (Malabarba & Weitzman, 1999).
Malabarba, L.R. and S.H. Weitzman. 1999. A new genus and species of South American fishes (Teleostei: Characidae: Cheirodontinae) with a derived caudal fin, including comments about inseminating cheirodontines. Proceedings of the Biological Society of Washington, 112: 410-431.
Acinocheirodon melanogramma is the only species of the genus. It was first diagnosed in 1998 by Malabarba in the work that defined the subfamily Cheirodontinae with cladistic tools, as recognized at the present. In that work, the specie was treated as “New Genus and Species B”, and it was recognized as a member of the tribe Compsurini (Malabarba, 1998).
Among the Cheirodontinae, Acinocheirodon melanogramma is closely related to the inseminating species that form the tribe Compsurini. The relationship of A. melanogramma with the remaining integrants of the tribe is still uncertain (Malabarba, 1998).
Maximum size registered for a male with 38 mm of standard length, from the tip of the snout to the base of the caudal fin (Malabarba & Weitzman, 1999).
This species present the body slightly elongated, terminal to subterminal mouth. Likewise all members of the subfamily Cheirodontinae, it only presents one tooth row in the premaxilla and dentary. The teeth are pedunculated with several cusps. There is no humeral spot and a pseudotympanum instead is present on the humeral region. Acinocheirodon melanogramma presents a lateral line completely pored and no scales covering the caudal-fin lobes. The body does not present any conspicuous coloration, except a dark spot on the end of the caudal peduncle and a slightly yellowish caudal fin.
GenBank sequences (Supplier: NCBI) Seven occurrences:
Acinocheirodon melanogramma voucher DCC38470 cytochrome oxidase subunit 1 (COI) gene, partial cds; mitochondrial 398 bp linear DNA (HQ600807.1 GI:317017421);
Acinocheirodon melanogramma voucher DCC38469 cytochrome oxidase subunit 1 (COI) gene, partial cds; mitochondrial 654 bp linear DNA (HM404965.1 GI:300198670);
Acinocheirodon melanogramma voucher DCC38467 cytochrome oxidase subunit 1 (COI) gene, partial cds; mitochondrial 654 bp linear DNA (HM404963.1 GI:300198666);
Acinocheirodon melanogramma voucher DCC38471 cytochrome oxidase subunit 1 (COI) gene, partial cds; mitochondrial 641 bp linear DNA (HM404966.1 GI:300198672);
Acinocheirodon melanogramma voucher DCC38468 cytochrome oxidase subunit 1 (COI) gene, partial cds; mitochondrial 580 bp linear DNA (HM404964.1 GI:300198668);
Acinocheirodon melanogramma voucher LBP8104-37551 cardiac muscle myosin heavy chain 6 alpha (Myh6) gene, partial cds 730 bp linear DNA (HQ289111.1 GI:343531101);
Acinocheirodon melanogramma voucher LBP8104-37551 16S large subunit ribosomal RNA gene, partial sequence; mitochondrial 586 bp linear DNA (HQ171403.1 GI:315110786).
There is no cytogenetic study about Acinocheirodon melanogramma.
IUCN threat status: Not evaluated (IUCN, 2012).