Tatiana S. Leite

Morphological assessment of the Octopus vulgaris species complex evaluated in light of molecular‐based phylogenetic inferences

Cryptic species are common in the ocean, particularly among marine invertebrates such as octopuses. Delineating cryptic species is particularly problematic in octopus taxonomy where the plasticity recorded among taxonomic characters often results in low resolution at the species level. This study investigated the morphological relationships among seven phylogenetic clades (identified using cytochrome c oxidase subunit I) of the broadly distributed Octopus vulgaris species complex and close relatives. Morphological analyses in this study were successful in delimiting O. sinensis, Brazilian O. vulgaris and O. vulgaris sensu stricto, which was congruent with the molecular findings of this study. Analyses based on male morphology were successful in distinguishing 14 of 15 total pairwise comparisons and proved to be a more reliable indicator of species‐level relationships in comparison with female morphology. The majority of characters with the greatest discriminatory power were male sexual traits. Significant morphological differences were also recorded among sampling localities of conspecifics, with phenotype showing correlation with local environmental data. The findings of this study support the hypothesis that multiple O. vulgaris‐like species are currently being incorrectly treated under a single species name, O. vulgaris. Octopuses being exported globally under the name O. vulgaris are of extremely high fisheries market value and profile. Our findings have potentially significant implications for the naming and conservation of commercially harvested members of this species complex throughout their ranges.

Atol das Rocas: an oasis for Octopus insularis juveniles (Cephalopoda: Octopodidae)

The habitat, population density, distribution and diet of Octopus insularis Leite & Haimovici, 2008 were studied in the Atol das Rocas Biological Reserve, based on visual census carried out in fixed quadrants. For each octopus den, we collected data on octopus size, substrate, type of den, and food remains around it. A total of 100 octopus dens were found within the fixed quadrants. The highest density occurred at Mapas area (0.30 inds/100 m2) and the lowest at Crista Algalica (0.07 inds/100 m2). The preferred den type was the one on the reef bed (69%), reinforcing the importance of rocky substrates for this species. A total of 454 food items, classified into 22 distinct taxa, were collected. The class Crustacea was best represented, accounting for 70.5% of the total prey, followed by Gastropoda (22.4%), Bivalvia (6.4%) and Cephalopoda (0.7%). Five species represented more than 80% of all findings: the crabs, Xanthodius denticulatus White, 1848 (38.5%), Microphrys bicornutus (Latreille, 1825) (18.5%) and Mithrax forceps Milne-Edwards, 1875 (7.0%); and the gastropods Hipponix sp. (9.3%) and Collisella sp. (8.4%). The overwhelming preference for small crabs shows that O. insularis is a specialized predator. The strong presence of juveniles inside the ring reef indicates the importance of this location for the development of this octopus species in northeastern Brazil.

Gonadal development and reproductive strategies of the tropical octopus (Octopus insularis) in northeast Brazil

Octopus insularis inhabits shallow waters along the coast and oceanic islands of northeastern Brazil, where it is the main target of commercial fishing of octopuses. This study aims to investigate the hypothesis that the tropical O. insularis has a distinct gonadal development and reproductive features when compare to its congener O. vulgaris from the subtropical regions. In order to describe its reproductive development, 545 octopuses were collected in the Northeastern Brazil. A good correspondence was observed between the gonad morphology and its histological structure. Oocytes in different development stages were observed in mature females. Most female in early maturity stages had sperm stored in the spermathecae, indicating that females copulate when still immature. There was no correlation between testis weight and the Needham complex, suggesting a protracted period of spermatophore production. Octopus insularis has a general gonadal development pattern similar to O. vulgaris, however, some differences were observed, as maturation at a smaller size, probably associated to a shorter life, and lower fecundity. The distinct reproductive features of O. insularis seem to be related to less variable conditions in the tropical environments. Management should take into account the differences and establish specific rules for the Northeast Brazil octopus fisheries.

First Description of the Eggs and Paralarvae of the Tropical Octopus, Octopus insularis, Under Culture Conditions

Abstract: Octopus insularis (Leite and Haimovici, 2008) occurs in a wide region of the tropical Atlantic, inhabiting shallow waters along the coast and oceanic islands of northeastern Brazil, where it is considered the primary target of octopus fisheries. This species was only recently described, and detailed information about its spawning, eggs, and paralarvae is unknown. The objective of this study was to estimate the fecundity, describe the eggs and paralarvae and the duration of embryonic development of O. insularis under culture conditions. Broodstock were captured and transported to the laboratory, where they were acclimated in a closed recirculation water system at 26 °C and 32 salinity. Eggs were obtained from two spawning females and were monitored throughout development; samples of 30 eggs were obtained 1 day after spawning and 1 day prior to the first hatching day, and their length, diameter and weights measured. The duration of embryonic development lasted from 30–38 days and fecundity was estimated as 85,000 eggs per female. The length and width of the eggs on the first day after spawning were 2.13 ± 0.06 mm and 0.82 ± 0.04 mm, respectively, and were 2.29 ± 0.06 mm and 0.92 ± 0.03 mm, respectively, one day before hatching. The newly hatched paralarvae exhibit 3 suckers per arm and a mean mantle length of 1.68 ± 0.13 mm. The chromatophore pattern of paralarvae is conspicuous, with ~ 90–111 chromatophores. A total of 32–40 and 56–69 chromatophores were found on the dorsal and ventral view, respectively. These results are of essential importance for identifying the eggs and paralarvae of O. insularis and in broadening our knowledge of this species.

Occurrence of Octopus insularis Leite and Haimovici, 2008 in the Tropical Northwestern Atlantic and implications of species misidentification to octopus fisheries management

The genus Octopus has been treated as a “catch all” taxon because many species have morphological similarities. To investigate the taxonomic status of the Octopus species in the Tropical Northwestern Atlantic (TNA) and the Tropical Southwestern Atlantic (TSA), we sampled Octopus insularis Leite and Haimovici, 2008 in three areas of the northeastern Brazilian coast, four Brazilian oceanic islands and one island in Western Caribbean, Mexico. Samples of Octopus maya Voss and Solís, 1966 were obtained from the cultivation center of the Universidad Nacional Autónoma de México (UNAM) in Sisal city. Specimens previously identified as Octopus vulgaris Cuvier, 1797 were collected in two regions of southeast Brazil, in an industrial port in Progreso city (southern Gulf of Mexico) and from a fish market in Isla Mujeres, Mexico (Western Caribbean). Molecular species attribution was completed based on morphology of fresh specimens identified by an octopus specialist and then checked against previous identification (cultivation center and GenBank sequences). Molecular analysis of both mitochondrial (cytochrome oxidase I) and nuclear genes (elongation factor-1α), including GenBank data, confirmed that one specimen collected at the Western Caribbean from Mexico and identified as O. insularis, shared the same haplotype of the species from the type locality, indicating the occurrence of this species in the Caribbean Sea. Phylogenetic analyses indicated that 21 GenBank sequences from TNA identified as O. vulgaris grouped within the O. insularis clade and are most likely to be to the latter species. The COI analysis also showed that 18 individuals collected in fishing landings and fish markets, previously identified as O. vulgaris, had the identical haplotype of O. maya collected in the UNAM cultivation center. These results corroborate the misidentification of species in Mexican fisheries. Based on molecular and morphological data we extended the distribution of O. insularis to the TNA and revealed cases of misidentification among the most commercially exploited octopus species in this region.

Different abilities to regulate tissue hydration upon osmotic challenge in vitro, in the cephalopods Octopus vulgaris and O. insularis

The spatial distribution of cephalopods is influenced by salinity and temperature. In marine osmoconformers, one reason for different spatial distributions maybe the putative distinct capacity to regulate tissue hydration. Adult Octopus vulgaris (n = 6) and O. insularis (n = 6) were obtained by divers from sites along the southern and northeastern Brazilian coasts, respectively. In the laboratory, octopuses were acclimated to full-strength seawater (salinity 34), for 5–10 days. They were then anesthetized (10 min in 4 °C seawater), a portion of the second right arm was removed, and cut into three portions. Tissues were placed in control isosmotic saline (osmolality 1072 mOsm/kg H2O). Fragments were weighed and transferred to either isosmotic, hyposmotic (50%), or hyperosmotic (150%) salines, and their weight was observed for 120 min. Tissue from both species maintained their hydration/weight following the hyposmotic shock, but differed in their response to the hyperosmotic challenge, where hydration remained unchanged in O. insularis, but was significantly reduced in O. vulgaris. This result could partially explain why O. insularis is more abundant than O. vulgaris throughout the shallow reefs and tide pools in the warmer and salty tropical waters of the northeastern Brazilian coast.

The Seven-arm Octopus, Haliphron atlanticus Streenstrup, 1861 (Cephalopoda, Alloposidae), in the Fernando de Noronha archipelago, Brazil

The rare deep-sea octopus, Haliphron atlanticus is the only known species recognized within the genus. A fragment of H. atlanticus was found in the Fernando de Noronha archipelago, Brazil (South Atlantic). Both phylogenetic reconstruction and pairwise genetic divergence show that the specimen recorded in South Atlantic is closely related to individuals from North Pacific. However, there is a greater divergence among these specimens and a giant octopus from North Atlantic. This evidence suggests that Haliphron is not monospecific, with at least two species, both represented in the Atlantic Ocean.