Based on the taxonomic system of Platnick in 2004, a total of 11 species of Myrmarachne are recognized from Taiwan. There are 4 species described as new species: M. exilisata sp. nov., M. lanyuensis sp. nov., M. luteopalpis sp. nov., and M. laticorseleta sp. nov., and 3 new records to Taiwan: M. annamita Zabka., 1985, M. edwardsi Berry, Beatty and Proszynski, 1996 and M. kiboschensis Lessert, 1925. And the species published in the past from Taiwan are recovered and redescribed in this study, namely, Myrmarachne formosana (Saito, 1933), Myrmarachne formosicola Strand, 1910 and Myrmarachne inermichelis Bösenberg and Strand, 1906 and Myrmarachne magna (Saito, 1933), and female of Myrmarachne formosana (Saito, 1933) and Myrmarachne formosicola Strand, 1910 are described and illustrated first time. Type specimen of M. formosicola Strand, 1910 was re-examined. We treat Pyroderes formosanus Matsumura, 1911 as a doubtful species. A taxonomic key of Myrmarachne from Taiwan, diagnoses, descriptions, quantitative character values, illustrations, locality records, and distribution maps are presented for the 11 recognized species.

Cyrba algerina is a salticid (Salticidae) spider that lives on the undersides of stones. Two populations were studied, Sintra and Algarve (Portugal), and shown to have similar phenology but different dominant prey. Life cycle in the laboratory was similar for the two populations, but Sintra matured at larger size than Algarve individuals, with these differences potentially having a genetic basis. Sintra individuals used prey-specific prey-capture behaviour against allopatric (Oecobius amboseli) and sympatric (O. machadoi, Trachyzelotes bardiae) spider and insect (bristletails) species. In contrast, Algarve C. algerina only adopted specialised capture behaviour against bristletails. Sintra, but not Algarve, individuals responded to the odour of O. machadoi and T. bardiae, and showed preference for T. bardiae over O. machadoi. Interpopulation variation in the use of specific prey-capture behaviour and in sensitivity to odour cues from prey is directly related to the prey available to individuals from each population, suggesting local adaptation to local prey. Preference for oecobiids seems to be controlled by an experiencetriggered developmental switch. The optics and histology of C. algerina’s principal eye suggest that living in a microhabitat with dim ambient light has favoured sensitivity at the expense of spatial acuity. Short focal length, reduced power of the eye’s diverging lens, and wide, contiguous rhabdomeres, seem to minimise the visual constraints imposed by the low light levels in C. algerina’s microhabitat. While relying solely on vision, C. algerina can detect, identify and capture prey in dim-light conditions under which other salticids perform poorly. C. algerina’s behaviour suggest use of temporal summation to improve its visual performance in dim light.

Evarcha culicivora, a species of jumping spider (Araneae: Salticidae from the Lake Victoria region of East Africa, has unusual prey-choice behaviour. It preferred prey is blood-carrying mosquitoes. It also has unusually complex mate-choice behaviour, with mutual mate choice being pronounced. This thesis is a study of E. culicivora’s prey-choice behaviour and mate-choice behaviour, as well as a study of processes underlying selective attention in this unusual species. E. culicivora uses olfaction in unique and often surprising ways. This includes identifying potential mates by odour alone, as well as choosing the odour of potential mates that have recently fed on blood-carrying mosquitoes. The odour of potential mates also primes both sexes for escalating conflict with potential rivals, as well as priming selective attention to the masked odour of specifically potential mates. Besides all this, the odour of blood-carrying mosquitoes primes E. culicivora to selectively attend to the masked odour of specifically this prey. Moreover, the appearance of blood-carrying mosquitoes and of potential mates primes E. culicivora to selectively attend to specifically the appearance of cryptic blood-carrying mosquitoes and cryptic potential mates, respectively. Vision and olfaction can even work together, with olfactory and visual cues from blood-carrying mosquitoes priming E. culicivora to selectively attend to the appearance and odour, respectively, of blood-carrying mosquitoes. Furthermore, E. culicivora has a poorly-understood relationship with two plant species, Lantana camara and Ricinus communis, and E. culicivora can identify these two plant species by odour alone. These plants may be relevant to this salticid as a nectar source by which it supplements its insect diet, but these plants may also be as sites at which E. culicivora males and females find potential mates, with E. culicivora’s interactions on these plants being especially exaggerated and complex.

Cyrba algerina is a salticid (Salticidae) spider that lives on the undersides of stones. Two populations were studied, Sintra and Algarve (Portugal), and shown to have similar phenology but different dominant prey. Life cycle in the laboratory was similar for the two populations, but Sintra matured at larger size than Algarve individuals, with these differences potentially having a genetic basis. Sintra individuals used prey-specific prey-capture behaviour against allopatric (Oecobius amboseli) and sympatric (O. machadoi, Trachyzelotes bardiae) spider and insect (bristletails) species. In contrast, Algarve C. algerina only adopted specialised capture behaviour against bristletails. Sintra, but not Algarve, individuals responded to the odour of O. machadoi and T. bardiae, and showed preference for T. bardiae over O. machadoi. Interpopulation variation in the use of specific prey-capture behaviour and in sensitivity to odour cues from prey is directly related to the prey available to individuals from each population, suggesting local adaptation to local prey. Preference for oecobiids seems to be controlled by an experiencetriggered developmental switch. The optics and histology of C. algerina’s principal eye suggest that living in a microhabitat with dim ambient light has favoured sensitivity at the expense of spatial acuity. Short focal length, reduced power of the eye’s diverging lens, and wide, contiguous rhabdomeres, seem to minimise the visual constraints imposed by the low light levels in C. algerina’s microhabitat. While relying solely on vision, C. algerina can detect, identify and capture prey in dim-light conditions under which other salticids perform poorly. C. algerina’s behaviour suggest use of temporal summation to improve its visual performance in dim light.

Orientador: Gustavo Quevedo Romero / Banca: Marcelo de Oliveira Gonzaga / Banca: Paulo Enrique Cardoso Peixoto / Resumo: A aranha Psecas chapoda (Salticidae) utiliza a planta Bromelia balansae (Bromeliaceae) como sítio de forrageamento, acasalamento e postura de ootecas, bem como abrigo contra predadores e berçário. Em contraste com outras espécies de salticídeos bromelícolas, que habitam até 7-8 espécies de bromélias em regiões litorâneas, P. chapoda habita quase exclusivamente B. balansae em regiões de Cerrado e margens de Florestas Semidecíduas. Esta especialização possivelmente ocorre porque as áreas de vida de P. chapoda são dominadas apenas por B. balansae, não havendo bromélias de outras espécies/arquiteturas disponíveis para as aranhas. Neste trabalho realizamos experimentos com os objetivos de: (1) testar se a associação de P. chapoda restringia-se a uma planta hospedeira específica ou a plantas com um tipo específico de arquitetura; (2) verificar se indivíduos adultos de P. chapoda escolhiam ativamente suas plantas hospedeiras e (3) determinar os mecanismos sensoriais envolvidos na seleção de plantas hospedeiras por P. chapoda. Nossos resultados mostraram que a especialização deste salticídeo por micro-hábitat não é espécie-específica e sim restrita a certas características arquiteturais das rosetas de suas plantas hospedeiras. Psecas chapoda, guiada por estímulos visuais, avalia e distingue estruturas físicas de micro-hábitats e seleciona ativamente plantas em roseta com folhas longas e estreitas. Este padrão é incomum entre predadores invertebrados, e, provavelmente, evoluiu em virtude da grande abundância de um tipo específico de micro-hábitat aliado a excelente acuidade visual de P. chapoda que possibilita a detecção eficiente de suas plantas hospedeiras / Abstract: Spiders are selective for microhabitat and foraging sites, especially regarding the physical structure of host plants. Yet, little is known about which sensorial mechanisms they use to evaluate and select substrata. In this study, we manipulated real plants and plants' photos to test which plant traits are used by the bromeliad-dwelling spider Psecas chapoda to find their hosts, and whether this selection is based on visual (i.e., shape, color) or tactile stimuli. We further examined if Psecas is able to recognize its preferred substratum when placed on plants with different architectures. Our results showed that Psecas uses visual cues to find its preferred microhabitat. Rosette shaped monocots (Agavaceae) was preferred over other monocots and dicots. In both experiments involving real bromeliads and black-and-white bromeliad pictures choice was restricted to rosettes having narrow and long leaves. However, spiders delayed to select bromeliad pictures, suggesting that selection is primarily based on plant morphological traits, but color may also play a significant role in plant choice. Females remained longer than males on experimental bromeliads. Males detected bromeliad architecture on photos faster than females. Since males are likely to be more vulnerable to predation than females, they may have developed a more accurate vision allowing them to find shelter more efficiently. The great visual acuity of P. chapoda associated with the widespread availability of B. balansae might have lead to the evolution of this unusual spider-plant association. Key words: Bromeliaceae, visual selection, visual cues, host plant selection, plant architecture, Salticidae / Mestre

Made available in DSpace on 2014-06-11T19:22:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-04-27Bitstream added on 2014-06-13T18:50:02Z : No. of bitstreams: 1 omena_pm_me_sjrp.pdf: 777571 bytes, checksum: 868d23f2e3488299d429c238b4fab2fd (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A aranha Psecas chapoda (Salticidae) utiliza a planta Bromelia balansae (Bromeliaceae) como sítio de forrageamento, acasalamento e postura de ootecas, bem como abrigo contra predadores e berçário. Em contraste com outras espécies de salticídeos bromelícolas, que habitam até 7-8 espécies de bromélias em regiões litorâneas, P. chapoda habita quase exclusivamente B. balansae em regiões de Cerrado e margens de Florestas Semidecíduas. Esta especialização possivelmente ocorre porque as áreas de vida de P. chapoda são dominadas apenas por B. balansae, não havendo bromélias de outras espécies/arquiteturas disponíveis para as aranhas. Neste trabalho realizamos experimentos com os objetivos de: (1) testar se a associação de P. chapoda restringia-se a uma planta hospedeira específica ou a plantas com um tipo específico de arquitetura; (2) verificar se indivíduos adultos de P. chapoda escolhiam ativamente suas plantas hospedeiras e (3) determinar os mecanismos sensoriais envolvidos na seleção de plantas hospedeiras por P. chapoda. Nossos resultados mostraram que a especialização deste salticídeo por micro-hábitat não é espécie-específica e sim restrita a certas características arquiteturais das rosetas de suas plantas hospedeiras. Psecas chapoda, guiada por estímulos visuais, avalia e distingue estruturas físicas de micro-hábitats e seleciona ativamente plantas em roseta com folhas longas e estreitas. Este padrão é incomum entre predadores invertebrados, e, provavelmente, evoluiu em virtude da grande abundância de um tipo específico de micro-hábitat aliado a excelente acuidade visual de P. chapoda que possibilita a detecção eficiente de suas plantas hospedeiras / Spiders are selective for microhabitat and foraging sites, especially regarding the physical structure of host plants. Yet, little is known about which sensorial mechanisms they use to evaluate and select substrata. In this study, we manipulated real plants and plants’ photos to test which plant traits are used by the bromeliad-dwelling spider Psecas chapoda to find their hosts, and whether this selection is based on visual (i.e., shape, color) or tactile stimuli. We further examined if Psecas is able to recognize its preferred substratum when placed on plants with different architectures. Our results showed that Psecas uses visual cues to find its preferred microhabitat. Rosette shaped monocots (Agavaceae) was preferred over other monocots and dicots. In both experiments involving real bromeliads and black-and-white bromeliad pictures choice was restricted to rosettes having narrow and long leaves. However, spiders delayed to select bromeliad pictures, suggesting that selection is primarily based on plant morphological traits, but color may also play a significant role in plant choice. Females remained longer than males on experimental bromeliads. Males detected bromeliad architecture on photos faster than females. Since males are likely to be more vulnerable to predation than females, they may have developed a more accurate vision allowing them to find shelter more efficiently. The great visual acuity of P. chapoda associated with the widespread availability of B. balansae might have lead to the evolution of this unusual spider-plant association. Key words: Bromeliaceae, visual selection, visual cues, host plant selection, plant architecture, Salticidae