Performance of the SSI development function compared with 33 other functions applied to 79 arthropod species' datasets.

The development rates of arthropods are temperature-dependent. Studies aiming to predict the dynamics of arachnid, crustacean, and insect populations in nature often require the derivation of development functions representing this phenomenon. A previous study (Quinn, B.K., 2017, J. Therm. Biol. 63, 65-77) identified 33 development functions commonly used in past studies on temperature-dependent development of arthropods, and illustrated that: (1) most of 99 past studies only applied one or few (2-5) development functions to their data without considering others; and (2) most of a subset of 79 studies' data were not fit with the actual best function for them, resulting in sometimes substantial differences in model performance and predictive ability. However, that study did not test the class of development functions based on theoretical enzyme thermodynamics, including the Sharpe-Schoolfield-Ikemoto (SSI) function. Herein, the meta-analyses done in that previous study were redone, after fitting all 79 reanalyzed datasets with the SSI function. Estimates of the intrinsic optimum temperature (TΦ) for development of each tested species were also derived using the SSI function and compared among taxa. Including the SSI function in analyses did not change the conclusions of the previous study concerning development function usage, choice, and consequences. Notably, the SSI function performed as well as or relatively better than other functions of comparable or lower complexity in terms of R2, AICC-based rankings, ΔAICC values, and prediction errors, which may recommend its more widespread use in future studies. Overall differences in TΦ were found among arthropod subphyla, as well as between most species pairs. Most TΦ estimates produced herein were novel, and could be used to make inferences about or comparisons among arthropod taxa in future studies.

Semideciduous seasonal forest opiliofauna (Arachnida, Opiliones), State of Paraná, Brazil

Harvestmen are arachnids that play an important role in organic matter breakdown. However, there are many ecosystems in Brazil, including Conservation Units, which lack information about these organisms or are sub-sampled. Even in areas of Atlantic forest, a biome that hosts the greatest diversity and endemic rates of these arthropods in the world. In this perspective, the purpose of this study was to survey the harvestmen fauna in areas of Semideciduous Seasonal Forest in the Ilha Grande National Park, Paraná, southern Brazil, from February to November 2019, totaling 15 days and 60 hours, on six islands in the Paraná River. A total of 170 specimens was collected, distributed in five genera, comprising two species and three morphotypes. The low species richness may reflect the isolation of populations imposed by the island effect, however the study expanded the geographic distribution of Parapachyloides uncinatus and Discocyrtus invalidus, for which until then there was no record of occurrence in the Paraná State.

Analysis of the Full-Length Pyriform Spidroin Gene Sequence.

Spiders often produce multiple types of silk, each with unique properties suiting them to certain tasks and biological functions. Orb-weaver spiders can generate more than six types of silk fibroins, with pyriform silk used to form attachment discs, adhering silk to other surfaces and substances. The unique higher-order structuring of silk fibroins has been cited as the source of their remarkable biomechanical properties. Even so, only one full-length gene sequence of pyriform silk protein 1 (PySp1) from Argiopeargentata has been reported, and studies on the mechanical properties of natural pyriform silk fibers are also lacking. To better understand the PySp1 family of genes, we used long-distance PCR (LD-PCR) to determine the sequence of PySp1 in the Araneusventricosus species. This full-length PySp1 gene is 11,931 bp in length, encoding for 3976 amino acids residues in non-repetitive N- and C-terminal domains with a central largely repetitive region made up of sixteen remarkably homogeneous units. This was similar to the previously reported A. argentata PySp1 sequence, with PySp1 from A. ventricosus also having a long repetitive N-linker that bridges the N-terminal and repetitive regions. Predictions of secondary structure and hydrophobicity of A. ventricosus PySp1 showed the pyriform silk fiber's functional properties. The amino acid compositions of PySp1 is obviously distinct from other spidroins. Our sequence makes an important contribution to understand pyriform silk protein structure and also provides a new template for recombinant pyriform silk proteins with attractive properties.

Occurrence and predictive utility of isochronal, equiproportional, and other types of development among arthropods.

In isochronal (ICD) and equiproportional development (EPD), the proportion of total immature (egg, larval, and/or juvenile) development spent in each stage (developmental proportion) does not vary among stages or temperatures, respectively. ICD and EPD have mainly been reported in copepods, and whether they occur in other arthropods is not known. If they did, then rearing studies could be simplified because the durations of later developmental stages could be predicted based on those of earlier ones. The goal of this study was to test whether different taxa have ICD, EPD, or an alternative development type in which stage-specific proportions depend on temperature, termed 'variable proportional' development (VPD), and also how well each development type allowed later-stage durations to be predicted from earlier ones. Data for 71 arthropods (arachnids, copepod and decapod crustaceans, and insects) were tested, and most (85.9%) species were concluded to have VPD, meaning that ICD and EPD do not occur generally. However, EPD predicted later-stage durations comparably well to VPD (within 19-23%), and thus may still be useful. Interestingly, some species showed a 'mixed' form of development, where some stages' developmental proportions varied with temperature while those of others did not, which should be further investigated.

Miniaturisation in Chelicerata.

Arachnids and their relatives (Chelicerata) range in body length from tens of centimetres in horseshoe crabs down to little more than 80-200 µm in several groups of mites. Spiders (Araneae) show the widest range within a given Bauplan - the largest species being ca. 270 times longer than the smallest - making them excellent models to investigate scaling effects. The two mite clades (Parasitiformes and Acariformes) are the main specialists in being small. Miniaturisation, and its consequences, is reviewed for both fossil and extant chelicerates. Morphological changes potentially related to miniaturisation, or adapting to the ecological niches that small size allows, include reduction in the length and number of legs, loss of prosomal arteries (and eventually also the heart), replacement of book lungs by tracheae, or even loss of all respiratory organs. There may also be evolutionary novelties, such as the acquisition of structures by which some mites attach themselves to larger hosts. The observed character distributions suggest a fairly fundamental division between larger pulmonate (lung-bearing) arachnids and smaller, non-pulmonate, groups which could reflect a phylogenetic dichotomy. However, it is worth noting that lineages of tiny spiders were originally fully pulmonate, but have acquired some typically non-pulmonate features, while camel spiders (Soli-fugae) can be large but have a Bauplan suggestive of smaller, non-pulmonate, ancestors.

The disjunct pattern of the Neotropical harvestman Discocyrtus dilatatus (Gonyleptidae) explained by climate-driven range shifts in the Quaternary: Paleodistributional and molecular evidence.

The disjunct distribution of the harvestman Discocyrtus dilatatus (Opiliones, Gonyleptidae) is used as a case study to test the hypothesis of a trans-Chaco Pleistocene paleobridge during range expansion stages. This would have temporarily connected humid regions ('Mesopotamia' in northeastern Argentina, and the 'Yungas' in the northwest, NWA) in the subtropical and temperate South American lowlands. The present study combines two independent approaches: paleodistributional reconstruction, using the Species Distribution Modeling method MaxEnt and projection onto Quaternary paleoclimates (6 kya, 21 kya, 130 kya), and phylogeographic analyses based on the cytochrome oxidase subunit I molecular marker. Models predict a maximal shrinkage during the warm Last Interglacial (130 kya), and the rise of the hypothesized paleobridge in the Last Glacial Maximum (21 kya), revealing that cold-dry stages (not warm-humid ones, as supposed) enabled the range expansion of this species. The disjunction was formed in the mid-Holocene (6 kya) and is intensified under current conditions. The median-joining network shows that NWA haplotypes are peripherally related to different Mesopotamian lineages; haplotypes from Santa Fe and Córdoba Provinces consistently occupy central positions in the network. According to the dated phylogeny, Mesopotamia-NWA expansion events would have occurred in the last glacial period, in many cases closely associated to the Last Glacial Maximum, with most divergence events occurring shortly thereafter. Only two (out of nine) NWA haplotypes are shared with Mesopotamian localities. A single, presumably relictual NWA haplotype was found to have diverged much earlier, suggesting an ancient expansion event not recoverable by the paleodistributional models. Different measures of sequence statistics, genetic diversity, population structure and history of demographic changes are provided. This research offers the first available evidence for the historical origin of NWA disjunct populations of a Mesopotamian harvestman.

Segmentation and tagmosis in Chelicerata.

Patterns of segmentation and tagmosis are reviewed for Chelicerata. Depending on the outgroup, chelicerate origins are either among taxa with an anterior tagma of six somites, or taxa in which the appendages of somite I became increasingly raptorial. All Chelicerata have appendage I as a chelate or clasp-knife chelicera. The basic trend has obviously been to consolidate food-gathering and walking limbs as a prosoma and respiratory appendages on the opisthosoma. However, the boundary of the prosoma is debatable in that some taxa have functionally incorporated somite VII and/or its appendages into the prosoma. Euchelicerata can be defined on having plate-like opisthosomal appendages, further modified within Arachnida. Total somite counts for Chelicerata range from a maximum of nineteen in groups like Scorpiones and the extinct Eurypterida down to seven in modern Pycnogonida. Mites may also show reduced somite counts, but reconstructing segmentation in these animals remains challenging. Several innovations relating to tagmosis or the appendages borne on particular somites are summarised here as putative apomorphies of individual higher taxa. We also present our observations within the concept of pseudotagma, whereby the true tagmata - the prosoma and opisthosoma - can be defined on a fundamental change in the limb series while pseudotagmata, such as the cephalosoma/proterosoma, are expressed as divisions in sclerites covering the body without an accompanying change in the appendages.

A multilocus phylogeny of Podoctidae (Arachnida, Opiliones, Laniatores) and parametric shape analysis reveal the disutility of subfamilial nomenclature in armored harvestman systematics.

The taxonomy and systematics of the armored harvestmen (suborder Laniatores) are based on various sets of morphological characters pertaining to shape, armature, pedipalpal setation, and the number of articles of the walking leg tarsi. Few studies have tested the validity of these historical character systems in a comprehensive way, with reference to an independent data class, i.e., molecular sequence data. We examined as a test case the systematics of Podoctidae, a family distributed throughout the Indo-Pacific. We tested the validity of the three subfamilies of Podoctidae using a five-locus phylogeny, and examined the evolution of dorsal shape as a proxy for taxonomic utility, using parametric shape analysis. Here we show that two of the three subfamilies, Ibaloniinae and Podoctinae, are non-monophyletic, with the third subfamily, Erecananinae, recovered as non-monophyletic in a subset of analyses. Various genera were also recovered as non-monophyletic. As first steps toward revision of Podoctidae, the subfamilies Erecananinae Roewer, 1912 and Ibaloniinae Roewer, 1912 are synonymized with Podoctinae Roewer, 1912 new synonymies, thereby abolishing unsubstantiated subfamilial divisions within Podoctidae. We once again synonymize the genus Paralomanius Goodnight & Goodnight, 1948 with Lomanius Roewer, 1923 revalidated. We additionally show that eggs carried on the legs of male Podoctidae are not conspecific to the males, falsifying the hypothesis of paternal care in this group.

First Amazonian species of Maracaynatum, with comments on the genus (Opiliones: Laniatores: Samoidae).

Among Opiliones, the family Samoidae Sørensen, 1886 is a group of small Laniatores with a wide tropical distribution. Neotropical samoids are distributed mainly in the Caribbean subregion, with species recorded from insular localities and the Venezuelan coastal range. Previously, for continental South America only three genera and just a few specimens of unidentified Samoidae have been recorded from Brazil. In this paper we describe Maracaynatum isadorae sp. nov., the first record of the genus for Brazil and the first samoid described for the Amazon biome. We also provide an emended diagnosis for the genus and a map with its distribution.

Morphological tricks and blessed genitalia: rectifying the family placement of Fijicolana tuberculata (Opiliones: Laniatores: Zalmoxidae).

The type specimens of Fijicolana tuberculata Roewer, 1963 were re-examined and the male genital morphology is illustrated and described for the first time. Despite the presence of several morphological features that are typical of Samoidae, such as the presence of scopulae on legs III and IV, genital morphology unambiguously indicates that this species belongs to the Zalmoxidae rather than to the Samoidae. Fijicolana Roewer, 1963 is newly synonymized with Zalmoxis Sørensen, 1886. However, the newly implied combination is preoccupied by Z. tuberculatus Goodnight & Goodnight, 1948 thus the replacement name Zalmoxis roeweri nom. nov. is proposed to avoid secondary homonymy. The definition of Z. roeweri nom. nov. is amended, and the morphology of this species is compared with other representatives of Zalmoxidae and Samoidae. We conclude that the presence of scopulae alone is not a sufficiently diagnostic characteristic for Samoidae and, therefore, correctly placing taxa into families within Samooidea + Zalmoxoidea requires additional morphological evidence (e.g. genital morphology). In light of this result, we point out that the "scopulated" Australasian samoids Badessania metatarsalis Roewer, 1949, Sawaiellus berlandi Roewer, 1949 and Parasamoa gressitti Goodnight & Goodnight, 1957 require re-examination in order to detect potential errors in their family placement.

Sinostoma yunnanicum, the first nemastomatine harvestman in China (Arachnida: Opiliones: Nemastomatidae).

The easternmost Nemastomatinae species, Sinostoma yunnanicum n. gen., n. sp., from northern Yunnan, China is described. It extends the geographic distribution of Nemastomatinae by roughly 3000 km southeastwards. Within Nemastomatinae Sinostoma displays plesiomorphic characters, including the long, basic bulb of the truncus shaft and the extremely short glans of penis, armed with short robust spines. Sinostoma may represent a relict line in the early evolution of nemastomatine harvestmen.

Characterization of Platymessa with redescription of the type species and a new generic synonymy (Arachnida, Opiliones, Cosmetidae).

The genus Platymessa was originally described by Mello-Leitão and diagnosed following the Roewerian system. It originally included two species from the Colombian Andes. Subsequently, a third species was described: Platymessa transversalis Roewer, 1963, which is herein transferred to the genus Chusgonobius Roewer, 1952, forming the new combination Chusgonobius transversalis. Herein, an emended diagnosis is given to Platymessa, the type species, Platymessa h-inscriptum Mello-Leitão, 1941, is redescribed and P. nigrolimbata Mello-Leitão, 1941 is considered its junior subjective synonym. Brachylibitia Mello-Leitão, 1941, is herein considered a junior subjective synonym of Platymessa and its type species, Brachylibitia ectroxantha Mello-Leitão, 1941, considered a species inquirenda, forming the new combination Platymessa ectroxantha. Genital morphology of Platymessa h-inscriptum is described and some characters are discussed regarding their importance in cosmetid taxonomy. Novel forms of sexual dimorphism are described in coxa IV.

Four new species of the spider genus Nesticella Lehtinen & Saaristo, 1980 from Laos, Thailand and Myanmar and the first description of the male of Nesticella yui Wunderlich & Song, 1995 with a proposed new diagnostic character for the family Nesticidae Simon, 1894 (Arachnida, Araneae).

During various expeditions to Laos between 2003 and 2012 and one expedition to Myanmar in 2014, spiders of the family Nesticidae were collected inside and outside of caves. This was the first time this family was encountered in Laos. All specimens belong to the genus Nesticella Lehtinen & Saaristo, 1980. Four species have been recognized as being new to science, which are described in this paper: Nesticella beccus n. sp. (male, female; LAOS: Bolikhamsay Province, Luang Prabang Province, Huaphan Province, Khammouan Province, THAILAND: Mae Hong Son Province), Nesticella laotica n. sp. (male, female; LAOS: Vientiane Province, Huaphan Province, Luang Prabang Province, Bolikhamsay Province), Nesticella foelixi n. sp. (male; LAOS: Bolikhamsay Province) and Nesticella michaliki n. sp. (male, female; MYANMAR: Chin State). The male of Nesticella yui Wunderlich & Song, 1995 is described for the first time and it is the first record for Laos. Results from a first micro-computed tomography analysis of a female copulatory organ for this genus are provided. This analysis proves that female Nesticella exhibit a complex functional receptaculum, which is highly complex within the genus. The presence of a special type of leg setae (pipette setae) in males is proposed as diagnostic for the family Nesticidae.

New Canadian records of Nemastoma bimaculatum (Fabricius), and a brief summary of introduced Eurasian harvestmen in North America (Arachnida, Opiliones).

Eurasian harvestmen have been introduced to, and have established themselves in North America. Species known to have been introduced include Trogulus tricarinatus (L.) 1767, Paroligolophus agrestis (Meade) 1855, Rilaena triangularis (Herbst) 1799, Oligolophus tridens (C. L. Koch) 1836, and Nemastoma bimaculatum (Fabricius) 1775, for the last of which new Canadian records (Ontario) are given below. It is not entirely determined if the species Phalangium opilio (L.) 1758, Opilio parietinus (DeGeer) 1778 and Mitopus morio (Fabricius) 1779 are introduced to North America, or are naturally of Holarctic distribution. The former seems the more likely hypothesis for the first two, but M. morio in North America may be native or may not be that species. Detailed descriptions and illustrations of all these species may be found in Martens (1978).

Catalogue of type materials of springtails (Hexapoda, Collembola) in the Canadian National Collection of Insects, Arachnids & Nematodes.

The catalogue assembles and updates all data concerning the type material of Collembola kept in the Canadian National Collection of Insects, Arachnids & Nematodes in Ottawa (CNC). Information is provided for type material of 69 species. Included are holotypes of 31 species (together with 5 ones from Cretaceous amber), syntypes of 26 species (four of them are presently considered to be junior synonyms) and paratypes of 32 species (one of which is considered a junior synonym). Essential label data, references to original descriptions, and modern status including synonyms are given.

Review of terminology for the outline of dorsal scutum in Laniatores (Arachnida, Opiliones).

In many Opiliones (notably the Laniatores) the five most anterior opisthosomal tergites are fused with the carapace forming the so called dorsal scutum (DS) (Latreille 1804; Simon 1879; Hadzi 1942) with a highly variable shape arising from multiple factors, such as differential development of musculature (especially of coxa IV), internal organs and influence of appendages (Loman 1903; Winkler 1957). The different degrees of fusion of the tergites were first studied by Hadzi (1942), who proposed a terminology for them. This terminology was adopted and enhanced by Kratochvíl (1958) and Martens (1978). A shield formed by the fusion of the carapace with abdominal tergites I to V is called scutum magnum (Hadzi 1942). The shield formed by the fusion of carapace with abdominal tergites I to VII is called scutum complexum (Kratochvíl 1958) and occurs in the males of Heteropachylinae Kury, 1994 (Kury 1994) and Paralolidae Kratochvíl, 1958 (Kratochvíl 1958). Finally, the scutum completum (Hadzi 1942) is formed by the complete fusion of the carapace and abdominal scutum, formed by tergites I to VIII, and occurs in the Sandokanidae (Martens 1978). In this paper we focus on the different forms of the scutum magnum.

Two new species of whip spider (Amblypygi): an epigean and a cave dwelling Charinus Simon, 1892 from Belize.

Central America is rich in whip spider species, mainly of the genera Phrynus and Paraphrynus (Phrynidae), but also includes few registers of Charinus (Charinidae) with no description of taxa. In this paper two new species of Charinus from Belize are described and illustrated (Charinus belizensis sp. nov. and Charinus reddelli sp. nov.) being the first species named from Central America. New records of Charinus victori Armas, 2010 from Puerto Rico, a comparative table listing the differential characters of the Caribbean and Central American species, and a distributional map of those species are also provided.

Taxonomic notes on the genus Auranus (Opiliones, Laniatores, Stygnidae), with description of two new species.

Among the Amazonian families of harvestmen the members of Stygnidae are better known due to the recent revision of the family and efforts of specialists describing new taxa in the last few years. Species of Amazonian genus Auranus Mello-Leitão, 1941, have been collected in several inventories that were carried out in different locations of the Amazon basin. In this paper we provide a new diagnosis for Auranus, and the description of two new species: Auranus leonidas sp. nov. and Auranus xerxes sp. nov. from the Brazilian states of Roraima and Amazonas, respectively. We also offer complementary genital descriptions of Auranus hehu Pinto-da-Rocha & Tourinho 2012, Auranus parvus Mello-Leitão, 1941, and Auranus tepui Pinto-da-Rocha & Tourinho 2012. Five species are recognized in Auranus, including the two new species described in this paper. The lamina parva modified into a calyx is proposed as putative synapomorphy for the genus Auranus. Therefore, A. hoeferscovitorum, which does not possess this character, is removed from Auranus. Instead we propose for it the new combination Verrucastygnus hoeferscovitorum comb. nov. We also provide a key to the males of Auranus, and a map with the distribution for all species examined in this work.

Cladistic analysis and description of three new species of the Chilean genus Nanophareus (Opiliones: Gonyleptidae: Pachylinae).

Three new species of the Chilean Pachylinae genus, Nanophareus Roewer, 1929 are described: N. bicornutus sp. nov. (Valle de Aconcagua, Zapallar, V Región de Valparaíso), N. maipu sp. nov. (La Rinconada, Quebrada de la Plata, Maipu, Región Metropolitana-Santiago), and N. polyhastatus sp. nov. (El Abanico, VIII Región de Bio-Bío). These three new species were included in a cladistic analysis that resulted in two equally most parsimonious trees (238 steps, C.I. = 0.38; R.I. = 0.51), corroborating the monophyly of Nanophareus. The proposed synapomorphies for Nanophareus remain largely unchanged: an external row of enlarged tubercles inserted amongst small ones on the lateral margin of dorsal scutum; the ventro-basal margin of the pedipalpal tibia curved at 90° in lateral view; and retrolateral seta on pedipalpal tibia with an apically bifid socket (socket and seta longer than pedipalpal tibia length), with additional small setae distally. The sister group of Nanophareus, as well as its subfamilial placement, are still unsettled issues that are here further discussed.

Revalidation of the Brazilian genus Discocyrtanus, with description of two new species (Opiliones: Gonyleptidae: Pachylinae).

The genus Discocyrtanus Roewer, 1929, is herein revalidated from the synonymy of Discocyrtus Holmberg, 1878, to include besides the type species Discocyrtanus goyazius Roewer, 1929, four other Brazilian species, two of them new-Discocyrtanus bugre sp. nov. and Discocyrtanus tocantinensis sp. nov.-and two newly transferred from Discocyrtus: Discocyrtanus oliverioi (H. Soares, 1945) comb. nov., and Discocyrtanus pertenuis (Mello-Leitão, 1935) comb. nov. Three species, Discocyrtus pectinifemur Mello-Leitão, 1937, Discocyrtus fimbriatus Mello-Leitão, 1939, and Discocyrtus canalsi Roewer, 1943, are considered junior subjective synonyms of Discocyrtanus pertenuis comb. nov.. A mix-up between labeling of original illustrations of two species of Discocyrtus described by Mello-Leitão is noted.