Interspecific, ontogenetic, and sexual variation in ozopore morphology among cosmetid harvestmen (Arachnida, Opiliones, Laniatores).

The ozopores of cosmetid harvestmen rest upon lateral projections of the carapace, have simple or highly reduced channels, and are partially obscured by enlarged dorsal processes associated with coxae I and II. Rather than use scent gland secretions to form a chemical shield on the dorsum, the cosmetid harvestman exhibits a unique defensive behavior known as "leg dabbing" in which the distal tip of tarsus I or II is dipped into fluid that accumulate at the base of coxa II and the droplet on the tarsus is pointed toward the predator. Relatively little is known about interspecific variation in ozopore morphology among cosmetid harvestmen. In this study, we used scanning electron microscopy to examine the ozopores of males and females of nine species as well as those of antepenultimate nymphs for two species. Among adults, we found differences between species in the shapes of the ozopores (round or subtriangular), the morphology of the dorsal and lateral channels (if present), and the relative size, shape and armature of the dorsal posterior process (dpp) of coxa I and the dorsal anterior process (dap) of coxa II. Our observations suggest that the morphology of dpp I and dap II could be sources for systematic characters in future phylogenetic studies of the Cosmetidae. We observed ontogenetic differences but relatively little intersexual variation in the morphology of the ozopore. The ozopores of nymphs are generally more oval than those of adults and the opening of the ozopore of the nymph is less obstructed, if at all, by the dorsal coxal processes of legs I-II. These morphological differences suggest that nymphs may use scent gland secretions in a manner different from that of adults.

Ontogenetic variation in the sensory structures on the pedipalps of cosmetid harvestmen (Arachnida, Opiliones, Laniatores).

In arachnids, pedipalps are highly variable appendages that may be used in feeding, courtship, defense, and agonistic encounters. In cosmetid harvestmen, adults have pedipalps that feature flattened femora, spoon-shaped tibiae, and robust tarsal claws. In contrast, the pedipalps of nymphs are elongate with cylindrical podomeres and are adorned with delicate pretarsi. In this study, we used scanning electron microscopy to examine the distribution of cuticular structures (e.g., sensilla chaetica, pores) on the elements of the pedipalps of adults and nymphs of three species of cosmetid harvestmen. Our results indicate that there is considerable ontogenetic variation in the morphology of the trochanter, femur, patella, tibia, and tarsus. The pretarsus of the nymph has a ventral patch of setae that is absent from the adult tarsal claw. We observed this structure on all three cosmetid species as well as on the pedipalps of an additional seven morphospecies of nymphs collected in Belize and Costa Rica. This structure may represent a previously unrecognized autapomorphy for Cosmetidae. Examinations of the pedipalps of antepenultimate nymphs of additional gonyleptoidean harvestmen representing the families Ampycidae, Cranaidae, Manaosbiidae, and Stygnidae revealed the occurrence of unusual, plumose tarsal setae, but no setal patches on the tarsal claw.

New record for the genus Platymessa Mello-Leitão, 1941 in Colombia, with the description of a new species (Opiliones, Cosmetidae).

The genus Platymessa Mello-Leitão, 1941 is represented by two species in the Andes of Colombia: P. h-inscriptum Mello-Leitão, 1941 and P. ectroxantha Mello-Leitão, 1941. Platymessa victoriae Pinzón-M. & Townsend, sp. n. is described on the basis of somatic morphological characters and the structure of the penis. The placement of this new species in the genus Platymessa is based upon multiple characters including the outline of dorsal scutum, the presence of a blunt spine on coxa IV, having short and strong legs with femora III and IV having five longitudinal rows of small tubercles, the shape of the basitarsomeres of male leg I, the distribution and relative sizes of the marginal setae on the ventral plate of the penis, and the morphology of the chelicerae and cheliceral sockets. In contrast to other members of the genus, P. victoriae has a pair of triangular tubercles on scutal area III, lacks paired paramedian tubercles on scutal area V, and does not have a ladder mask color pattern on the dorsal scutum. The description of this species expands the distribution of the genus to north of the Oriental Cordillera in the Cesar Department of Colombia.

Leg injuries and wound repair among cosmetid harvestmen (Arachnida, Opiliones, Laniatores).

Previous studies of leg injuries in harvestmen have focused on the fitness consequences for individuals that use autospasy (voluntary detachment of the leg) as a secondary defense mechanism. Leg damage among non-autotomizing species of laniatorean harvestmen has not been investigated. Under laboratory conditions, we damaged femur IV of Cynorta marginalis and observed with scanning electron microscopy (SEM) the changes in these wounds over ten days. We also used SEM to examine leg damage from individuals of three species of cosmetid harvestmen that were collected in the field. On the basis of changes in the external surface of the hemolymph coagulum, we classified these wounds as fresh (coagulum forming), recent (coagulum with smooth surface), older (coagulum is scale-like with visible cell fragments), and fully healed (scale replaced by new cuticle growth on the terminal stump). Our observations indicate that wound healing in harvestmen occurs in a manner comparable to that of other chelicerates. Leg injuries exhibited interspecific variation with respect to the overall frequency of leg wounds and the specific legs that were most commonly damaged. In addition, we measured walking and climbing speeds of adult C. marginalis and found that individuals with fresh injuries (lab-induced) to femur IV walked at speeds significantly slower than uninjured adults or individuals collected from the field that had fully healed wounds to a single leg. J. Morphol. 278:73-88, 2017. ©© 2016 Wiley Periodicals,Inc.

Interspecific variation in the microanatomy of cosmetid harvestmen (Arachnida, Opiliones, Laniatores).

Scanning electron microscopy (SEM) is a useful tool for identifying interspecific variation in often overlooked structures that may represent useful sources for informative phylogenetic characters. In this study, we used SEM to compare the morphology of 12 cosmetid species from Central America, the Caribbean, and North America including multiple species for the genera Cynorta, Erginulus, and Paecilaema. To determine if microanatomical structures were unique to the cosmetid taxa under examination, we investigated the microanatomical structures of six additional species of gonyleptoidean harvestmen representing the families Agoristenidae, Cranaidae, Gonyleptidae, Manaosbiidae, and Stygnidae. Our results indicate that the shape of the ocularium (narrow, intermediate, or broad) did not vary within cosmetid genera, whereas the morphology of the rough pit glands on the eye mound varied considerably between species. Each cosmetid species had 10-20 rough pit glands on the ocularium whereas only the eye mounds of Avima intermedia (Agoristenidae) and Glysterus sp. (Gonyleptidae) had similar structures. With regards to the surface texture of the dorsal scutum, cosmetid harvestmen exhibited a rivulose-microgranulate morphology (6 species), a microtuberculate-rivulose-microrgranulate morphology (4 species), or a microgranulate morphology (2 species). In contrast, each of the gonyleptoidean species exhibited a microgranulate pattern, with the exception of Stygnoplus clavotibialis, which had a rivulose-microgranulate surface texture. For cosmetid harvestmen, we observed considerable interspecific variation in the shape and number of teeth on the fixed and moveable fingers of the male chelicerae. Similarly, we also observed interspecific variation in the distribution and shape of tubercles on the ventral and dorsal surfaces of the femur of the pedipalp. Overall, our results indicate that there are several microanatomical structures associated with the ocularium, dorsal scutum, male chelicera, and pedipalp that could represent informative phylogenetic characters in future taxonomic studies of cosmetid harvestmen.

Ovipositor morphology of cosmetid harvestmen (Arachnida, Opiliones, Laniatores): a new source of informative characters.

The external morphology of the penis is an important source of systematic characters in phylogenetic studies of harvestmen. Modern taxonomic studies generally include micrographs generated by scanning electron microscopy (SEM) to illustrate penis morphology. In contrast, the external morphology of the ovipositor has largely been ignored for harvestmen belonging to the suborder Laniatores. Comparative studies of ovipositor microanatomy using SEM are especially lacking for species belonging to the superfamily Gonyleptoidea. In an effort to determine if the ovipositor could be a useful source of informative characters for these harvestmen, we investigated interspecific variation in the external morphology of the ovipositor for 14 species from the family Cosmetidae. Our SEM-based study revealed that the external surface of the distal tips of the ovipositors of most species was generally divided into four symmetrical lobes, although we observed a bilobed condition in Erginulus clavotibialis and Erginulus subserialis. The distal surfaces were also generally smooth, with the exception of the ovipositor of Erginulus weyerensis, which featured small surface setae. In addition, we observed considerable interspecific variation in the morphology of the peripheral setae on the distal tip, especially with respect to relative size, morphology of the shaft, and number, symmetry, and shapes of the distal tips. The functional significance, if any, of variation in the structure of the peripheral setae is unclear. Additional behavioral studies of copulation and oviposition are needed to determine the functional relationships between reproductive morphology and behavior. The morphological variation that we observed suggests that future taxonomic studies of cosmetid harvestmen, and potentially other gonyleptoidean taxa, would benefit from the inclusion of descriptions of ovipositor morphology.

Reproductive morphology of three species of neotropical harvestmen (Opiliones, Laniatores, Gonyleptoidea).

Illustrations of penis morphology are essential components of species descriptions for harvestmen belonging to the suborder Laniatores. Male genitalia are important sources of taxonomic characters and are generally assumed to exhibit relatively little intraspecific variation. In contrast, descriptions of female reproductive morphology are rarely included in taxonomic descriptions of laniatorean harvestmen. As a result, relatively little is known about variation in the external features of the ovipositor. In this study, we used scanning electron microscopy to examine variation in male and female reproductive morphology among three species of harvestmen that are members of the superfamily Gonyleptoidea. Specifically, we examined the microanatomy of penises and ovipositors of Cynortula granulata (Cosmetidae), Phareicranaus calcariferus (Cranaidae), and Rhopalocranaus albilineatus (Manaosbiidae). Our results support the general observation that male reproductive morphology is conservative and displays little intraspecific variation. We observed considerable intraspecific variation in the number and shape of marginal setae on the ventral plate of the penis, but little or no variation in the morphology of the distal border of the ventral plate or the shape of the glans penis or stylus. With respect to female genitalia, we observed considerable intraspecific variation in the number of peripheral setae on the distal tip of the ovipositor. We also observed interspecific variation in the morphology of the peripheral setae (surface of the shaft and at shape of the distal tip), the distribution and morphology of smaller setae on the external surface of the ovipositor, and the surface texture of the external lobes. Our results indicate that there are several features associated with ovipositor morphology among laniatorean harvestmen that may represent potentially informative taxonomic characters.

Morphological changes during postembryonic development in two species of neotropical harvestmen (Opiliones, Laniatores, Cranaidae).

Morphological changes during postembryonic development in the Cranaidae are described on the basis of the examination of an incomplete series of larvae, nymphs, and adults of Phareicranaus calcariferus and Santinezia serratotibialis. The life histories of these species are hypothesized to consist of six nymphal stages, featuring the appearance of secondary male sexual characteristics in the antepenultimate nymph (N5). Color and body shape change dramatically during development. Growth rates for nymphs based upon leg measurements were similar for both species. In S. serratotibialis, the greatest increase in leg size occurred from larva to 1st nymph. The tarsomeres of legs I-IV varied by 1-2 segments per leg for each nymph stage, with the number of tarsal segments increased by 1-2 segments at each stage. Adults had nearly twice as many tarsomeres on leg II than other legs. Ontogenetic changes were observed in the armature of the proximal cheliceral segment, ocularium, pedipalp, opisthosoma, distitarsus III and IV, and leg IV. Morphological changes in postembryonic development in cranaid harvestmen are similar to those reported for other Laniatores.

Morphology and ultrastructure of the Malpighian tubules of the Chilean common tarantula (Araneae: Theraphosidae).

Relatively little is known about the morphology and ultrastructure of the Malpighian tubules of spiders (Arachnida: Araneae). Our study represents the first investigation of the Malpighian tubules of a theraphosid spider and is the only study to examine the living Malpighian tubules using confocal laser scanning microscopy. In theraphosid spiders, the Malpighian tubules originate from the stercoral pocket in the posterior portion of the opisthosoma and extend forward toward the prosoma in a dendritic pattern. There are three distinct segments (initial, main, and terminal), all dark brown in appearance. Each segment has distinctive ultrastructural features. Both the terminal and the main segment appear to be composed of at least two cell types with finger-like cytoplasmic protrusions associated with one of these types. The terminal segment, which is most proximal to the stercoral pocket, is the largest in diameter. It is composed of large, cuboidal cells containing many mitochondria and lipid inclusions. The main segment is intermediate in diameter with many mitochondria and secretory vesicles present. The initial segment is relatively thin in comparison to the other segments and is intimately associated with the digestive gland. The cells of the initial segment contain very little cytoplasm, fewer mitochondria, secretory vesicles, and prominent inclusions.

Ultrastructure of the cuticular scales of lynx spiders (Araneae, Oxyopidae) and jumping spiders (Araneae, Salticidae).

The cuticular scales of spiders are flattened setae that may occur in a diverse array of colors and shapes on the dorsal and lateral surfaces of the prosoma, opisthosoma, and walking legs. In this study, we used transmission electron microscopy (of both sections and wholemounts) and scanning electron microscopy (in concert with paraffin carving) to examine the internal anatomy and ultrastructure of the cuticular scales of several species of lynx spiders (Oxyopidae) and jumping spiders (Salticidae). We also examined iridescent and noniridescent pigmented scales for species in both families. In addition to discovering intra- and interspecific and sexual differences in scale ultrastructure, the results of our research also indicate that the ultrastructure of the scales of these spiders varies directly with coloration. For iridescent scales, we found a general absence of trabeculae, a lack of pigment granules, and an almost complete fusion of the the upper and lower laminae. For noniridescent scales, we observed granules, well-formed trabeculae, and a complex internal structure consisting of internal elements within the lumen of the scale. Our examination of the scales of these spiders represents the first complete description of the ultrastructure of the cuticular scales of any species of spider. J. Morphol. 240:77-92, 1999. © 1999 Wiley-Liss, Inc.

The cuticular scales of Lynx spiders (Araneae, Oxyopidae).

An examination of the cuticular scales of the lynx spiders Oxyopes aglossus, O. salticus, and Peucetia viridans using scanning electron microscopy revealed that scales in these spiders are morphologically distinct, yet similar to the scales of the jumping spiders Eris militaris and Hentzia mitrata. Like the cuticular scales of jumping spiders, the cuticular scales of lynx spiders exhibit morphological differentiation in regard to location of occurrence on the body, with scales near the eyes tending to have more numerous and larger spines on the superior surface than scales on other regions of the prosoma and opisthosoma. The functional significance of this differentiation in scale morphology is unknown. Sexual dimorphism and ontogenetic variation in scale morphology and color were observed in the genus Oxyopes,but not in Peucetia. In addition, the scales of P. viridans were distinguishable from the scales of Oxyopes spp. on the basis of the number of apical spines (1 in P. viridans instead of 3-7 in Oxyopesspp.) and on the presence of spines on the inferior surface (many in P. viridans and none in Oxyopesspp.). J. Morphol. 236:223-231, 1998. © 1998 Wiley-Liss, Inc.