A new species of parasitic isopod (Bopyroidea: Ionidae) infesting burrowing shrimp (Axiidea: Callianassidae) in the tropical eastern Pacific.

A new species of parasitic isopod in the genus Ione Latreille, 1818, infesting the branchial chamber of the intertidal burrowing shrimp Neotrypaea tabogensis (Sakai, 2005) is described on the basis of material collected on the Pacific coast of Costa Rica. Diagnostic features of the new species include: (1) body shape of female asymmetrical with slight left distortion, pereon segments distinct; (2) head of female not fused with first pereomere, posterior margin nearly straight; (3) antenna of female composed of five articles; (4) posterior lamella of barbula of female with two tapered lobes on each side; (5) body of male elongated, clearly segmented dorsally; (6) head of male completely separated from the first pereomere; and (7) maxillipeds absent in male. This is the seventh valid species in the genus Ione and the first record of this genus from the tropical eastern Pacific. A key for identification of species of Ione is also provided.

Monogamy in the Burrowing Shrimp Axianassa australis Rodrigues & Shimizu, 1992 (Decapoda, Gebiidea, Axianassidae).

Our knowledge of the mating systems in burrowing shrimps (infraorders Axiidea and Gebiidea) is still rather limited. Here we describe the burrow use pattern, sex ratio, and sexual dimorphism of the burrowing shrimp Axianassa australis to test for monogamy, considering that monogamous species live in heterosexual pairs and exhibit a low degree of sexual dimorphism. To this end, a total of 226 individuals of A. australis were collected from the northeast region of Brazil. Our results showed that A. australis inhabited its burrows mainly as pairs, most of which were male-female pairs. In agreement with the expectations, specimens of A. australis were found dwelling as heterosexual pairs more frequently than expected by chance alone. The presence of ovigerous females was associated with the burrow occupation; that is, brooding females were more frequently observed in male-female combinations than solitarily. Also supporting theoretical considerations, we did not observe sexual dimorphism in body size between males and females of the population and the different categories of the burrow occupation. Conversely, sexual dimorphism in cheliped size was evident in the population, with larger chelipeds in males than in females. This observation agrees with that reported for most burrowing shrimps in which male-male competition is the main evolutionary force of sexual selection. The observations above favor the hypothesis that A. australis is primarily monogamous, with a small fraction of the males moderately promiscuous.

Validation of the ghost shrimp species Neocallichirus pinheiroi Hernáez, Windsor, Paula amp; Santana (Decapoda: Callianassidae) from the southwestern Atlantic.

Hernáez et al. (2020) described a new species of ghost shrimp, Neocallichirus pinheiroi, from northeastern coast of Brazil, Western Atlantic. Although the description and figures presented by Hernáez et al. (2020) fully characterize the new species, the journal issue in which the description appeared was published online only, and the article in which N. pinheiroi appeared did not include a ZooBank registration number (LISD), required for validation of new names in electronic-only publications [vide Art. 8.5.3 of the amended Code of the International Commission on Zoological Nomenclature (ICZN, 1999, 2012)]. As result, the name Neocallichirus pinheiroi Hernáez, Windsor, Paula Santana, 2020, is not available according the International Code of Zoological Nomenclature (ICZN, 1999, 2012). Therefore, the present note serves to validate the name Neocallichirus pinheiroi by fulfilling the ICZN conditions for nomenclatural availability.

Validation of the Pleistocenic ghost shrimp Callichirus santensis Hernáez, Buchmann amp; Santana† (Decapoda: Callianassidae) from the southwestern Atlantic.

Hernáez et al. (2020) described a new fossil species of ghost shrimp, Callichirus santensis, from the Upper Pleistocene Cananéia Formation, southeast Brazil. The article in which C. santensis† was originally proposed was published online only (Hernáez et al., 2020), but did not include a ZooBank registration number (LISD), required for validation of the new names in electronic-only publications [vide Art. 8.5.3 of the amended Code of the International Commission on Zoological Nomenclature (ICZN, 1999, 2012)]. Therefore, the present note serves to validate the name Callichirus santensis by fulfilling the ICZN conditions for nomenclatural availability.

A new species of Biffarius Manning amp; Felder, 1991 (Decapoda: Axiidea: Callianassidae) from the intertidal coast of northeastern Brazil.

A new species of intertidal ghost shrimp, Biffarius botterae, is described from Maranhão and Ceará in northeastern Brazilian coast. Diagnostic features of the new species include: (1) antennular peduncle shorter than antennal peduncle; (2) male major cheliped massive; (3) male pleopod 2 uniramous, vestigial; (4) uropodal endopod widening distally, inner lateral margin convex; and (5) anterodorsal plate of uropodal exopod absent. Biffarius Manning Felder, 1991, now consists of four species: B. biformis (Biffar, 1971), B. botterae sp. nov., B. delicatulus Rodrigues Manning, 1992, and B. limosus (Poore, 1975). A key to the species of Biffarius is provided.

A new species of Callianidea H. Milne Edwards, 1837 (Decapoda, Axiidea, Callianideidae) from the Pacific Coast of Central America, with key to the genus.

A new callianideid species, Callianidea mariamartae n. sp. is described from the Pacific coast of Costa Rica. The material is compared with the type description of C. laevicauda Gill, 1859 and C. typa H. Milne Edwards, 1837. Diagnostic features of the new species include a linea thalassinica very short, lateral margin of carapace with a distinct hepatic groove, accessory respiratory filaments unsegmented, outer uropodal ramus with strong longitudinal carinae. This is first record of the genus from eastern Pacific of Central America and third report of the family from world. A key for identification of the species belonging to the genus is provided in this document.

Population biology of the burrowing shrimp Callichirus seilacheri (Decapoda: Callianassidae) in northern Chile

La historia natural de los camarones fantasma, conocidos por modelar la estructura de las comunidades en hábitats de aguas someras, ha sido poco estudiada en el Pacífico suramericano. Aquí presentamos información ecológica concerniente a Callichirus seilacheri, con base en individuos recolectados entre enero y diciembre de 2003 en playa Las Machas, norte de Chile. La densidad de las madrigueras varió entre 1.4 y 20.2 madrigueras / 0.25 m2, y fue mayor durante el verano (18.2 madrigueras / 0.25 m2). La proporción de sexos fue 1:1 durante la mayor parte del periodo de estudio; sin embargo, las hembras superaron en número a los machos en enero y setiembre. Los machos presentaron un tamaño máximo mayor al de las hembras (27.1 y 24.0 mm CL, respectivamente). La presencia de juveniles se restringió principalmente al periodo comprendido entre febrero y mayo. La madurez sexual se alcanza a un tamaño de CL de 20.8 mm en los machos y 18.1 mm en las hembras. El periodo reproductivo principal se extendió del otoño al invierno (de mayo a agosto, con un pico en junio), y coincidió con temperaturas decrecientes en el agua y con la presencia de una capa de sedimento sobre las madrigueras.

The life history of ghost shrimps, known for their role in shaping community structures in shallow water habitats, is poorly studied in species occurring along the coasts of the South American Pacific. Here we present ecological information concerning Callichirus seilacheri based upon individuals collected from January to December 2003 in Las Machas beach, northern Chile. Burrow densities varied between 1.4 and 20.2 burrows / 0.25 m2, and was highest during summer (18.2 burrows / 0.25m2). The sex proportion was 1:1 during most of the study period; however, females outnumbered males in January and September. Males reached a larger maximum size than females (27.1 and 24.0 mm CL, respectively). The presence of juveniles was restricted principally to the time between February and May. Sexual maturity was reached at a size of 20.8 mm (males) and 18.1 mm CL (females). The main breeding period lasted from autumn to winter (May to August, peaking in June), and co-occurred with decreasing water temperatures and the presence of a sediment layer covering the burrows.