Idiomysis bumbumiensis sp. nov., a new mysid species (Mysida, Mysidae, Anisomysini) from Southeast Asia

We provide a detailed description, including illustrations, of a new species of mysid belonging to the genus Idiomysis W. M. Tattersall, 1922 from Pulau Bum Bum, Sabah, Malaysia. The presence of two segments of antennal scale, a shorter endopod of uropod than the exopod and a pair of minute spines at the apex of the telson distinguishes Idiomysis bumbumiensis sp. nov. from all other species in the genus. The present species is the seventh member of the genus Idiomysis and it is the first described in Southeast Asia. It is also the third species of tribe Anisomysini discovered in Malaysian waters. We include an updated dichotomous key of all Idiomysis species.

A new genus and species of groundwater isopod of the family Protojaniridae (Isopoda: Asellota: Gnathostenetroidoidea) from southern Chile

A new asellotan isopod of the family Protojaniridae Fresi, Idato & Scipione, 1980 is described from freshwater springs in the Osorno province, Los Lagos region, southern Chile. Wiyufiloides osornoensis gen. & sp. n. is the third South American protojanirid species and the first known groundwater isopod in Chile. The new genus and species is principally characterized by the presence of a vestigial antennal scale, a strongly subchelate pereiopod I and the absence of an apical lobe on the protopod of pleopod II. The new taxon is described in detail and figures are given.

Heteromysoides taramensis, a new species of mysid (Mysida: Mysidae) from an anchialine cave on Tarama Island, Ryukyu Islands, southwestern Japan

Heteromysoides taramensis, a new species of the family Mysidae (Mysida) is described from an anchialine cave on Tarama Island, Ryukyu Islands, southwestern Japan. This species differs from its congeners by the following combination of characters: eyes subrectangular in dorsal aspect without process; cornea developed; telson distally rounded, 1.3 times as long as maximum width, with 5 or 6 pairs of simple spines distolaterally, 1 pair of long simple spines subapically and 1 pair of short simple spines apically; antennal scale elongated elliptical, extending to distal margin of antennular peduncle; antennal sympod with distomesial corner produced into blunt tooth; and endopod of third thoracopod with simple, not subchelate, termination.

Taxonomic discrimination of species of the genus Metapenaeus Wood-Mason, 1891 from Indian waters through morphometric and molecular studies

The present study identified useful characters in the discrimination of species of the genus Metapenaeus, viz., Metapenaeus affinis, M. alcocki, M. brevicornis, M. dobsoni, M. kutchensis, M. monoceros and M. moyebi, in Indian waters, on the basis of morphometric and molecular studies. Out of 40 morphometric measurements, a correlation matrix of 14 morphometric measurements: carapace width, carapace depth, length of rostrum, of antennular peduncle, of telson, and of 6th abdominal somite; 6th abdominal somite depth, antennal scale length, merus length of 1st pereopod, movable finger length of 1st pereopod, movable finger length of 2nd pereopod, movable finger length of 3rd pereopod, merus length of 5th pereopod, and carpus length of 5th pereopod, were all found to be important in discriminating those seven species. The generated classification matrix showed 100% accurate classification of six species, except M. kutchensis (87.09%). DNA barcodes (588 bp) were generated for Metapenaeus brevicornis, M. dobsoni, M. ensis, M. kutchensis and M. monoceros. A simple identification key is thus proposed for nine species of Metapenaeus from Indian waters.

Description of the second juvenile stage of the blue-fingered burrowing crayfish Parastacus caeruleodactylus (Decapoda: Astacidea: Parastacidae)

This study describes and illustrates the morphology of the second juvenile stage of the blue-fingered burrowing crayfish Parastacus caeruleodactylus. One female carrying 20 juveniles was collected in January 2019 from a swamp forest in the municipality of Dom Pedro de Alcântara, state of Rio Grande do Sul, southern Brazil. Juveniles were dissected and the appendages were mounted in slides. The general morphology and the pattern of attachment of the second juvenile stage of P. caeruleodactylus correspond to that reported for other parastacids. The main differences among the co-generic species are related to the number of articles in the flagella of the antennae, the number of spines in the antennal scale, the number of setae in the articles of the appendages, the number of teeth in the mandible molar and incisor processes, the absence of segmentation in the exopod flagellum of the maxillipeds and the number of teeth in the crista dentata of the ischium of maxilliped 3.

Antennal scales improve signal detection efficiency in moths

The elaborate bipectinate antennae of male moths are thought to increase their sensitivity to female sex pheromones, and so should be favoured by selection. Yet simple filamentous antennae are the most common structure among moths. The stereotypic arrangements of scales on the surface of antennae may resolve this paradox. We use computational fluid dynamics techniques to model how scales on the filamentous antennae of moths affect the passage of different particles in the airflow across the flagellum in both small and large moths. We found that the scales provide an effective solution to improve the efficacy of filamentous antennae, by increasing the concentration of nanoparticles, which resemble pheromones, around the antennae. The smaller moths have a greater increase in antennal efficiency than larger moths. The scales also divert microparticles, which resemble dust, away from the antennal surface, thereby reducing contamination. The positive correlations between antennal scale angles and sensilla number across Heliozelidae moths are consistent with the predictions of our model.

A new species of Philocheras (Decapoda: Caridea: Crangonidae) from Western Australia, with a key to all species of this genus worldwide

One new species and three new distribution records for the family Crangonidae (Crustacea: Decapoda) are reported from Western Australia. A new species, Philocheras gardenensis sp. nov. is described and illustrated based on specimens collected from the Western Australia. The new species closely resembles Philocheras fasciatus (Risso, 1816), but can be distinguished easily by the absence of lobe-like folds on either side of the middle line of the carapace, the presence of a lateral carina extending from the branchiostegal spine, the longer middorsal carina and distolateral tooth of the antennal scale. A key for the genus Philocheras is provided, including currently, a total of 58 species and subspecies reported worldwide. Range extensions of three Crangonid shrimps are reported within Australia, and they are Philocheras obliquus (Fulton & Grant, 1902), Pontocaris arafurae (Bruce, 1988) and Vercoia gibbosa Baker, 1904.

Description of Idiomysis diadema sp. nov. (Mysida, Mysidae, Anisomysini), associated with Diadema urchins in the Red Sea; with nomenclatorial notes on its genus

The mysid Idiomysis diadema sp. nov. is described from small swarms hovering between the spines of the sea urchin Diadema setosum (Leske, 1778) at the reef flat of Dahab, Red Sea. The most striking characters within its genus are the subdivided antennal scale, endopod of uropods longer than exopod, and a pair of minute spines on the terminal margin of the telson. With this first description, a total of six Idiomysis species are now known, two of which are associated with cnidarians and only the new one with echinoids. An updated definition is given for the genus Idiomysis W. M. Tattersall, 1922, in order to match the current species inventory. To avoid previously incorrect and ambivalent gender attribution, I propose using the feminine gender for this genus throughout. Consequently, the spelling of two of its taxa, I. mozambica Deprez, Wooldridge & Mees, 2001, and I. robusta Connell, 2008, is changed.

Megalopa of Mesocrangon intermedia (Decapoda: Crangonidae) from the eastern part of the Sea of Okhotsk

For the first time megalopa of Mesocrangon intermedia is described. The megalopa can be distinguished from that of the Crangon and Neocrangon by the morphology of its telson and carapace. The main distinguishing features of megalopa of M. intermedia were two spines on medial line of the carapace, a relatively long rostrum, a relatively narrow antennal scale, and the distinctive length of the terminal setae on the telson. Drawings of general view and individual limbs are presented.

Description of the ‘stargazer mysid’ Mysidopsis zsilaveczi sp. nov. (Mysida, Mysidae, Leptomysinae) from the Cape Peninsula, South Africa

Mysidopsis zsilaveczi sp. nov. shows colour patterns on the eye that mislead the observer in thinking that the eyes are facing upwards, largely irrespective of their actual orientation, and have resulted in local divers naming these animals ‘stargazer mysids’. To date, only males of the new species could be sampled. Within the species-rich genus Mysidopsis G. O. Sars, 1864 the males of M. zsilaveczi are characterized, besides their unique colour patterns, by a subdivided antennal scale; by a small, mid-dorsal protuberance on the carapace; by endopods of all pleopods having a large, expanded, plate-like exite on the basal segment; by the comparatively large, two-segmented endopod of pleopod 1; by uropodal endopods that extend well beyond the telson; and by having a linguiform telson with spines all along its lateral margins. The new species also shows diverse, very small, lobe-like structures on basis and dactylus of thoracic endopods 3-8. Closely similar structures were for the first time also found in Mediterranean material of M. angusta G. O. Sars, 1864 and M. gibbosa G. O. Sars, 1864. This new species raises the number of southern African Mysidopsis species to nine, confirming the coastal waters of this subcontinent as being one of the major hotspots of diversity in this genus. An updated key to the Mysidopsis species from southern Africa (Namibia plus South Africa) is provided.