Pappose Setae Research Articles

External morphology of newly-hatched juveniles of Aegla lata (Crustacea, Aeglidae)

ABSTRACT Aegla is a genus of freshwater anomuran Crustacea known for having epimorphic postembryonic development. The newly-hatched juveniles’ morphology have been described for only 11 of the 93 known species. These descriptions are important tools for identifying juveniles and useful characteristics for phylogenetic analyses. This study aims to describe and illustrate the external morphology of the first juvenile stage of Aegla lata. Ovigerous females were collected, fed, and monitored periodically in the laboratory until the eggs hatched. The newly-hatched juveniles were fixed in an alcohol series and preserved in a 70% alcohol and glycerine solution (2:1 ratio) for subsequent dissection and analysis under light microscopy. The appendages were illustrated using a camera lucida and then described. Scanning electron microscopy was used to analyse some specimens, allowing the detailed observation of the setal morphology, some cephalothoracic appendages, and lineae aeglicae. Pappose setae were also observed in the protopod and dactylus of cheliped. The newly-hatched juvenile of A. lata has a set of the following characteristics: basal segment of antennule with serrate setae; distal segment of antennule with pappose setae; merus of second maxilliped with simple setae; and merus of third maxilliped without simple setae.

Description of three new species of Hyalella Smith, 1874 (Crustacea: Amphipoda) from Southeast Mexico.

Lacandona tropical rainforest is an area with an important hydrological and biological role in Mexico, nevertheless there are few studies about freshwater macrofauna. In this study, we described three new species collected in three different water bodies in the Lacandona tropical rainforest: H. parva from lake Nahá with a minute body size without mucronations on pleonites 1-2, H. montebellensis from lake La Esmeralda with two dorsoposterior carinae on pleonites 1 and 2 (mucronations) and one seta almost at mid-ventral margin of gnathopod 1, and H. lacandonis from lake Península with minute dorsal mucronations on pleonites 1-2 and 2-3 setae on the hind margin of basis of gnathopod 1. Hyalella montebellensis n. sp. and H. lacandonis n. sp. have almost the same number of articles in flagellum of antennae 1-2, both species present four pappose setae on the inner plate of maxilla 1 and telson subquadrate, longer than wide.

Functional morphology of comminuting feeding structures of Trichodactylus borellianus (Brachyura, Decapoda, Trichodactylidae), an omnivorous freshwater crab

Crustaceans exhibit great diversity of feeding structures with morphological traits that are useful to infer the general trophic habits of species. In this study, we analyzed the functional morphology of comminuting feeding structures (mandibles, chelipeds, gastric mill) of the freshwater crab Trichodactylus borellianus directly related with the food fragmentation. The heterochely and mechanical advantage (MA) of the chelae were also studied. In both analyses, we considered the relationship between morphology and the natural diet. We expected to find a consistent relation between feeding habits and morphological traits. In general, we found simple structures armed with uniform setal systems and feeding appendages without pronounced teeth or spines. Mandibles have primarily cutting functions, helping with the food anchoring and fragmentation with mandibular palps armed with pappose setae. Chelipeds were covered with spines and simple setae. Adult males exhibited right-handedness with high MA of the major chelae. The ingested, relatively large pieces of food are finally chewed by a gastric mill equipped with sharp cusps characteristic of decapods with low ingestion of crude fiber material. The morphology of the feeding apparatus revealed that it is well adapted to an omnivorous diet, being able to cope with dietary changes.

The genus Uromunna (Crustacea: Isopoda: Munnidae) in New South Wales, Australia, with a key for all known species

ABSTRACTThe invertebrate collection of the Australian Museum revealed the existence of three new species of the genus Uromunna (family Munnidae) from New South Wales, Australia. Uromunna tenagoika sp. nov. from Batemans Bay has the head anterior margin concave, without simple setae; eyes with few ommatidia, eye lobes with both margins parallel, in male posterior margin directed forward; pereonite 7 as wide as pereonite 6, subequal to pleotelson width; pleotelson distal margin pointed, suburopodal shelf present; mandible palp absent; pereopod I propodus robust setae absent; pereopods relatively short; pleopod IV exopod distal tip with one pappose seta. Uromunna rhamnda sp. nov. from Batemans Bay has a head anterior margin concave, without simple setae; eye lobes with both margins parallel, in male posterior margin parallel to frontal margin; pleotelson distal margin pointed, suburopodal shelf absent; mandible palp present; pereopod I propodus robust setae absent; pleopod IV exopod distal tip with one pappose seta. Uromunna eora sp. nov. was found at Southern Creek, located north of Sydney and is the first species of the genus described from a fully freshwater environment with no marine water input. It has a relatively elongate body (length 3.4× width), anterior margin concave, eye lobes with both margins converging distally, in male posterior margin directed forward; pereonite 7 as wide as pereonite 6, wider than pleotelson width; pleotelson distal margin truncate, suburopodal shelf present; mandible palp present; pereopod I propodus robust setae present; pleopod IV exopod distal tip with two pappose setae. This work raises the number of Uromunna species found in Australia to a total of six.http://zoobank.org/urn:lsid:zoobank.org:pub:D877FC47-BC6E-4827-BA89-3A75AFDE1124

Setal morphology of grooming appendages in the spider crab, Libinia dubia.

In crustaceans, grooming behaviors decrease fouling by removing debris from the exoskeleton and body structures; these grooming behaviors improve respiration, sensory reception, movement, and reproduction. Setal morphologies of the following grooming appendages in the decapod crustacean spider crab Libinia dubia are examined including the first pereiopod (cheliped), first, second, and third maxillipeds (mouthparts), and first, second, and third epipods (internal extensions of the maxillipeds). The objective of this study was to describe setal morphologies of these grooming appendages and to elucidate possible functions and efficiencies of setal structures. Spider crabs are hypothesized to have elaborate setal morphologies, mainly for cleaning specialized decorating setae as well as for cleaning inside the gill chamber, which has a higher likelihood of becoming fouled compared to other decapods such as shrimps. Fourteen setal types are documented and included several varieties of serrate and pappose setae as well as simple setae, cuspidate setae, papposerrate setae, and canoe setae. Maxillipodal epipods in the gill chamber are free of fouling, suggesting the setation on the third maxilliped protopod has an efficient functional morphology in removing debris before water enters the gill chamber. Serrate setae may function for detangling and separating structures whereas pappose setae may function for fine detailed grooming. The cheliped is the only grooming appendage that can reach decorating setae and it contains only pappose setae; thus decorating setae is not likely groomed in a manner that would greatly decrease fouling. J. Morphol. 277:1045-1061, 2016. © 2016 Wiley Periodicals, Inc.

Ontogenetic Development of Sensory Structures on the Antennules and Antennae of the Giant River PrawnMacrobrachium rosenbergii(De Man)

In this study the occurrence of sensory structures on the antennules and antennae of the giant river prawn Macrobrachium rosenbergii (De Man) during postembryonic ontogenetic development were examined. Larvae and postlarvae were obtained from hatchery recirculating tanks, juveniles from indoor nursery tanks, and adults from earthen grow-out ponds. The animals were fixed with Karnovsky fixative and dissected. Antennules and antennae were removed, metal-coated, and photodocumented using a scanning electron microscope. The antennules have aesthetascs and simple plumose and pappose setae; the antennae have simple, plumose and pappose setae. These structures increase in density, covered surface, and distribution during ontogeny and should be related to chemoreception and mechanoreception. The antennular statocyst that appears during larval stage VII of the giant river prawn has an array of sensory structures that enable the perception of chemical and tactile stimuli beginning with its early life stages. The ontogenetic changes observed allow an inference that initial-stage larvae, advance-stage larvae, juveniles, and adults have different capacities to exploit the environment.

Hyalella cenotensis, a new species of Hyalellidae (Crustacea: Amphipoda) from the Yucatán Peninsula, Mexico.

In this study the first blind species of Hyalella for Mexico is described; it is the second in the genus to be recorded there. The new species is closer to the eyeless species: H. anophthalma Ruffo, 1957, H. muerta Baldinger, Shepard & Threloff, 2000, H. caeca Pereira, 1989, H. spelaea Bueno & Cardoso, 2011 in Cardoso et al. 2011, H. imbya Rodrigues & Bueno, 2012 in Rodrigues et al. 2012, but with no curved seta at the inner ramus of uropod 1, antennae 1 shorter than antennae 2, no apical setae on the telson and a characteristic dorsoposterior carina and three pappose setae on the inner plate of maxilla 1. The morphological intraspecific variations that can be found in this genus are discussed.

Setae for Gill-Cleaning and Respiratory-Water Circulation of Ten Species of Japanese Ocypodid Crabs

Abstract The setae of gill-cleaning mechanisms and respiratory-water circulation system of ten species of ocypodid crabs are described. Epipodal setae are classified as of four types: anchor-, scale setule-, simple-, and digitate-scale-setule setae. A few short setae are found on the Milne Edwards aperture (MEA) in Ocypode, while long plumo-pappose setae were found on the MEA in Uca. The basal part of the epipod of third maxilliped (EpMp3) is armed with many pappose setae having digitate-scale setules in Uca. On the other hand, only a few setae are found on the basal part of the EpMp3 in Ocypode. The constricted setae were dominant on Muller's aperture. Setae on these structures were compared with those of previous studies.

Behavioral and morphological aspects of decorating in Oregonia gracilis (Brachyura: Majoidea)

Abstract. Decorator crabs (Brachyura: Majoidea) are known for attaching sessile organisms to specialized velcro‐like hooked setae. Here we describe behavioral and morphological aspects of decorating for a common northern Pacific majoid, Oregonia gracilis. Members of O. gracilis decorate with a diverse array of sessile organisms. These are attached to hooked setae, and also physically interact with long, pappose setae that occur in the same body regions as hooked setae. We describe these pappose setae and document the occurrence of similar setae in 36 other decorating majoids across seven families. In O. gracilis, the density of pappose and hooked setae independently covary with decoration amount, which is sexually dimorphic—juveniles and adult females decorate heavily, whereas adult males decorate sparsely. Adult males have reduced numbers of hooked and pappose setae, but the ontogenetic patterns for the two setal types are different, suggesting that they are quasi‐independent characters. We experimentally ablated pappose setae to ask if they functionally contribute to decorating in O. gracilis. Surprisingly, we found that pappose setae are not necessary for decorating under laboratory conditions. Pappose setae could play an auxiliary mechanical role or a sensory role in decorating, or may have another as‐yet‐unidentified function distinct from decorating.

Hyalella armata (Crustacea, Amphipoda, Hyalellidae) and the description of a related new species from Lake Titicaca

Hyalella armata (Faxon, 1876) was considered for a long time to be a monotypic species. The peculiar morphology, very distinct from other species in Lake Titicaca, was not analysed in detail after the original description. However, the present authors' study of an extensive collection from The Natural History Museum in London has revealed two morphologically distinct species. Descriptions of H. armata and the new species H. longispina are given. Diagnosis of Hyalella longispina n. sp. (Figs 1, 2): Body (Fig. 1) with a posterior dorsal transverse ridge on every segment. Coxae 1 to 4 acuminate. Coxa 4 excavated posteriorly, and with deep acumination at right angle to sagittal body plane. Lateral process of coxa 4 strongly elongate (Fig. 2), distance between left and right process apices longer than body length (that distance shorter than body length in H. armata). Eyes pigmented. Antenna 1 shorter than antenna 2. Antenna 2 less than half body length. Mandible incisor toothed. Maxilla 1 palp uniarticulate, longer than wide, reaching more than half the distance between base of palp and tip of setae on outer plate; inner plate slender, with two strong and pappose apical setae. Maxilla 2 inner plate with one strong pappose seta on inner margin. Gnathopod 1 propodus quadrangular (length less than twice maximum width), hatchet-shaped, inner face with more than ten pappose setae, distoposterior and distoanterior borders without setose scales. Gnathopod 2 propodus triangular, palm longer than posterior margin, slope oblique, anterior edge with a small process. Telson wider than long, apically rounded, with more than two short simple setae, arranged symmetrically on the apical margin. Lateroventral sternal gills present on segments 3 to 7. Types and locality: Holotype male, 10 mm; PERU, Lake Titicaca, Choccocoyo Bay, St. P 6, GIC 481, 11-23 m, leg. Crawford, 25.VI.1937. Paratypes (collecting data as holotype): allotype female, 9 mm; 106 males, 6-10mm; 93 females, 5-10 mm. All deposited at The Natural History Museum, London (holotype: 2002.311; allotype: 2002.312; other paratypes: 2002.313-322).

Gill-Cleaning Mechanisms of the Mud Lobster Thalassina anomala (Decapoda: Thalassinidea: Thalassinidae)

The gill-cleaning mechanisms of the mud lobster Thalassina anomala were examined. The gill complement consists of 12 arthrobranchs and 5 podobranchs, both having cylindrical flattened filaments. Morphological inference suggested passive gill-cleaning mechanisms involving various setal systems; multidenticulate setae (on scaphognathite, setobranch, distal epipod), pappose setae (on coxae, proximal epipod), serrate setae (short setal tufts on limb coxae), and plumose setae (on carapace fringe). Smooth setae were found on the thoracic epimeron (inner wall of the branchial chamber) and inner branchiostegal margin. Small lamellar protrusions on the pereiopodal arthrodium were noted bearing dense pappose setae. The multidenticulate scaphognathite and epipodal setae were serrate distally. The digitate scale setules of multidenticulate setobranch, epipodal, and scaphognathite setae shared similarities: (1) digitation pattern gradually changes distally from angular to linear, (2) proximal setules incline toward the base while distal setules incline toward the tip with overlapping inclinations in a transition zone, and (3) setule density increases distally on the setal shaft. The multidenticulate scaphognathite setae have a V-form spiral arrangement on the distal part of the shaft, which is atypical in decapods. Aquarium observations did not show active gill cleaning by thoracic limbs, but general body grooming and respiratory reversal were observed. The phyletic relationships of gill-cleaning mechanisms, with notes on branrchial morphology, are discussed.

Feeding mechanisms in the barnacle Tetraclita squamosa (Bruguière)

T. squamosa is a suspension-feeding planktivore which augments its zooplankton diet with microplankton by microfiltration. The movements of mouthparts and maxillipeds were directly examined within the living animal by inserting an endoscope between the opercular plates. The mandibular palps function to remove particles trapped between themselves and the maxillae as well as enlarging the preoral cavity to accept food items. The maxillae can perform simultaneous and alternating movements which manipulate prey within the preoral cavity. The maxillules with their comblike setae pierce and tear the prey with simultaneous and alternating movements. Simultaneous and alternating contractions of the mandibles occur slightly later and complete the slicing and grinding mechanisms of food ingestion. The cirral activity of T. squamosa includes: testing, strong pumping beat, normal beat and extension. T. squamosa also displays opercular beak rotation through 360° following any period of cirral activity. In extension, the cirral fan can be held for up to 8 s and may rotate through 90° in relation to microcurrents. Microfiltration is achieved during pumping beat, strong pumping beat and normal beat, when currents induced by body movements allow microparticles to be trapped by the pappose setae of cirri I, which flank the oral cone.

Cuticular hair organs evoking reflexive closing and opening of the crayfish claw

1. 1. Cuticular hair organs on the index of the propus of the chelae of the crayfish Procambarus simulons simulons Faxon evoke reflexive closing and opening of the dactyl when stimulated by touch. 2. 2. These receptor organs are arranged in eight linear fields (A-H), with each row innervated by a separate branch of an afferent nerve. 3. 3. Nerve branches A and F innervate receptors on either side of the cutting edge of the propus; these organs trigger claw closing. Branches B and G innervate receptors driving both claw opening and closing; branchs C, D, E and H innervate hair organs that drive claw opening. 4. 4. The hair organs, which consist of groups of simple or pappose setae, can be divided into four types based on morphology. 5. 5. The cuticular hair organs show directional sensitivity.