Description of a new genus and five new species of tube-dwelling spider family Segestriidae (Araneae: Synspermiata) from Odisha, India

The six-eyed spider family Segestriidae is poorly documented from India, with only five species belonging to two genera. Here we describe a new genus, Indoseges gen. nov. with five new spp. viz. I. malkhangiri sp. nov., I. sushildutta sp. nov., I. chilika sp. nov., I. narayani sp. nov. and I. satkosia sp. nov. from Odisha. The first two spp. are described based on both male and female specimens and the rest on females only. The new genus resembles the genus Ariadna Audouin, 1826; still, males differ with respect to first leg spines, shape and position of apophysis and in the palp structure, and females having distinct spination in palp tarsi and femur of first two legs, and in the genitalia structure. Along with a distribution map of the Segestriids of India this paper also provides natural history information about the new genus, a discussion on its relationship with Ariadna, and the putative synapomorphies that define its placement in the subfamily Ariadninae.

First endemic arachnid from Isla Sala y Gómez (Motu Motiro Hiva), Chile: a new species of tube-dwelling spider (Araneae: Segestriidae)

The Isla Sala y Gómez or Motu Motiro Hiva is located 415 km northeast of Rapa Nui (Easter Island) and 3420 km from the coast of northern Chile. It is a small oceanic island (2.5 km2) dominated by volcanic rock with very little vegetal cover. Here, we describe the first endemic arachnid for the island, Ariadna motumotirohiva sp. nov. Females are similar to those of Ariadna perkinsi Simon, 1900 from Hawaiʻi and Ariadna lebronneci Berland, 1933 from the Marquesas in the dorsal dark abdominal pattern, but they differentiate from the latter in the anterior receptaculum, promarginal cheliceral teeth and leg IV macrosetae. A recent survey of the arachnid fauna of Rapa Nui, which included Motu Nui and the rocky shores, did not record the presence of the family Segestriidae, neither has it been found during previous surveys. However, it is not possible to discard the possibility of a local extinction on Rapa Nui and survival on Sala y Gómez. This study suggests other endemic terrestrial arthropods could be present on this very small and remote island.

Morphology of putative chemosensory setae in males of the spider genus Ariadna Audouin (Araneae, Synspermiata, Segestriidae)

Chemoreception in spiders plays an important role in prey detection, conspecific recognition and recognizing chemical cues in the environment. Sexually dimorphic structures often suggest a role in mating and there are not many papers describing sexual dimorphism in chemosensory setae in spiders. In this study, we present the first detailed morphological description of scopulate putative chemosensory setae in the palpal tarsi (cymbium) and in the distal segments of the legs of adult males of seven species of the spider genus Ariadna (Segestriidae) [A. araucana Grismado, A. boliviana Simon, A. corticola Lawrence, A. maxima (Nicolet), Ariadna sp. 1 (AUS), Ariadna sp. 2 (AFR-CONT), Ariadna sp. 3 (AFR-MAD)]. Our results show three different grouping configurations of five morphologically different types of scopulate setae (types a–e). This is the first detailed description of this type of setae on legs of a Synspermiata spider contributing to the knowledge of the morphology of different types of sensilla in this group of spiders. Our findings show that the scopulated setae of Ariadna do not seem to be homologous to the pseudoscopula of Mesothelae and Mygalomorphae. We also discuss how our findings relate to previous hypotheses of female sex pheromone detection and support during copulation.

The taxonomy of the American Ariadna Audouin (Araneae: Synspermiata: Segestriidae).

The spider genus Ariadna Audouin, 1826 currently comprises 102 of 127 described species of Segestriidae. Its distribution comprises all continents (except Antarctica), but it is mostly found on the tropical and subtropical regions. We present a comprehensive taxonomic revision of Ariadna in the American continent, including 2,519 specimens (i.e., type and non-type) from 30 arachnological collections. We present 31 nominal species, among which eight species are new to the science: Ariadna reginae n. sp. from Central America; Ariadna aurea n. sp., Ariadna caparao n. sp., Ariadna gaucha n. sp., Ariadna ipojuca n. sp., Ariadna lemosi n. sp. and Ariadna ubajara n. sp. from Brazil; and Ariadna lalen n. sp. from Chile. Nine species are proposed as junior synonyms: A. pragmatica Chamberlin, 1924 and A. scholastica Chamberlin, 1924 with A. bicolor (Hentz, 1842), A. gracilis Vellard, 1924 and A. conspersa Mello-Leitão, 1941 with A. obscura (Blackwall, 1858), A. murphyi (Chamberlin, 1920) with A. tarsalis Banks, 1902, A. pusilla (Nicolet, 1849) and A. ashantica Strand, 1916 with A. maxima (Nicolet, 1849), A. dubia Mello-Leitão, 1917 with A. boliviana Simon, 1907, and A. spinifera Mello-Leitão, 1947 with A. mollis (Holmberg, 1876). Ariadna comata O. P.-Cambridge, 1898 is revalidated. Two species became nomina dubia: Ariadna solitaria Simon, 1892 and A. tubicola Simon, 1893. The allotype of A. crassipalpa described by Camargo (1950) and the paratype of A. levii described by Grismado (2008), were identified as A. mollis and A. maxima, respectively and have been considered as misidentifications. The male of A. cephalotes and A. comata, and the female of A. calilegua are described for the first time.

The taxonomy of the American Ariadna Audouin (Araneae: Synspermiata: Segestriidae)

The spider genus Ariadna Audouin, 1826 currently comprises 102 of 127 described species of Segestriidae. Its distribution comprises all continents (except Antarctica), but it is mostly found on the tropical and subtropical regions. We present a comprehensive taxonomic revision of Ariadna in the American continent, including 2,519 specimens (i.e., type and non-type) from 30 arachnological collections. We present 31 nominal species, among which eight species are new to the science: Ariadna reginae n. sp. from Central America; Ariadna aurea n. sp., Ariadna caparao n. sp., Ariadna gaucha n. sp., Ariadna ipojuca n. sp., Ariadna lemosi n. sp. and Ariadna ubajara n. sp. from Brazil; and Ariadna lalen n. sp. from Chile. Nine species are proposed as junior synonyms: A. pragmatica Chamberlin, 1924 and A. scholastica Chamberlin, 1924 with A. bicolor (Hentz, 1842), A. gracilis Vellard, 1924 and A. conspersa Mello-Leitao, 1941 with A. obscura (Blackwall, 1858), A. murphyi (Chamberlin, 1920) with A. tarsalis Banks, 1902, A. pusilla (Nicolet, 1849) and A. ashantica Strand, 1916 with A. maxima (Nicolet, 1849), A. dubia Mello-Leitao, 1917 with A. boliviana Simon, 1907, and A. spinifera Mello-Leitao, 1947 with A. mollis (Holmberg, 1876). Ariadna comata O.P.-Cambridge, 1898 is revalidated. Two species became nomina dubia: Ariadna solitaria Simon, 1892 and A. tubicola Simon, 1893. The allotype of A. crassipalpa described by Camargo (1950) and the paratype of A. levii described by Grismado (2008), were identified as A. mollis and A. maxima, respectively and have been considered as misidentifications. The male of A. cephalotes and A. comata, and the female of A. calilegua are described for the first time.

Revision of the spider genus Gippsicola Hogg, 1900 (Araneae: Segestriidae).

Gippsicola Hogg is one of the four genera included in the family Segestriidae. Currently this monotypic Australian genus is represented by Gippsicola raleighi Hogg, 1900, a species described based on an immature specimen from Victoria, Australia. In this work we present a taxonomic revision of this genus, with an elucidative diagnosis, redescribing G. raleighi based on detailed morphologic characters of adult male specimens. Also, we are describing three new species: Gippsicola robusta n. sp. and G. lineata n. sp., both represented by males and females, and G. minuta n. sp., only known by the male. We provide some enlightenment on the systematics of Gippsicola and putative synapomorphies for the subfamily Segestriinae.

Revalidation of the spider genus Citharoceps Chamberlin, 1924 (Araneae, Segestriidae).

Citharoceps Chamberlin was diagnosed by the presence of a very distinctive stridulatory apparatus composed of two patches of ridges on the sides of the cephalic region, and a stridulatory thorn on the prolateral region of the femur I. Currently, this genus is a junior synonym of Ariadna Audouin, with the assumption that the stridulatory apparatus could constitute an exclusive feature of its unique known species, Citharocepsfidicina Chamberlin, currently senior synonym of Citharocepscalifornica Chamberlin & Ivie. In the present study, Citharoceps is revalidated and redescribed based on the occurrence of the stridulatory apparatus in Citharocepsfidicina and Segestriacruzana Chamberlin & Ivie, and also on the presence of distinguishable characters, such as the length of the labium-sternum junction, ventral median spine on male metatarsi I, and strong sclerotized interpulmonary fold in females, forming a conspicuous median flap. Segestriacruzana is transfered to Citharoceps, with Citharocepscalifornica removed from the synonym of Citharocepsfidicina, and proposed as a junior synonym of Citharocepscruzana, due to the similarity between the additional material examined and the original description. Males of Citharocepsfidicina and Citharocepscruzana are described for the first time.

Comparative cytogenetics of seven Ctenidae species (Araneae).

The present study elevates the number of cytogenetically analyzed ctenid species and genera from two to eight and six, respectively, presenting comparisons between chromosomal data obtained and the phylogenetic hypothesis proposed in the literature. Six ctenid species presented 13 autosomal pairs, exhibiting either X1X2O (Ctenus ornatus, Ctenus sp., Parabatinga brevipes and Phoneutria nigriventer) or X1X2X3O sex chromosome systems (Nothroctenus sp. and Viracucha andicola). Asthenoctenus borellii showed 2n ♂ = 20 + X1X2O. In all species, the chromosomes were telocentric. Some cells of one C. ornatus specimen exhibited one extra chromosome that, considering the behavioral similarities between the two chromosomes, can be considered to be supernumerary, derived from or giving rise to a sex chromosome. Silver impregnation revealed nucleolar organizer regions on one autosomal pair of C. ornatus and P. nigriventer (Cteninae) and two pairs of V. andicola (Acanthocteninae). Chromosomal data suggests that the X1X2X3O system arose several times in the evolution of entelegyne spiders, and that conversion of an X1X2O system into an X1X2X3O system and vice-versa has been a relatively common event in spiders. All the chromosomal data corroborate the close relationship between Ctenus and Phoneutria, the placement of P. brevipes within Cteninae, the placement of Anahita in a separated branch within Cteninae, and the inclusion of A. borellii in a distinct group within the ctenids (Viridasiinae), all of which are as proposed by phylogenetic hypotheses available in the literature.