Dragonfly Neurons Selectively Attend to Targets Within Natural Scenes.

Aerial predators, such as the dragonfly, determine the position and movement of their prey even when both are moving through complex, natural scenes. This task is likely supported by a group of neurons in the optic lobe which respond to moving targets that subtend less than a few degrees. These Small Target Motion Detector (STMD) neurons are tuned to both target size and velocity, whilst also exhibiting facilitated responses to targets traveling along continuous trajectories. When presented with a pair of targets, some STMDs generate spiking activity that represent a competitive selection of one target, as if the alternative does not exist (i.e., selective attention). Here, we describe intracellular responses of CSTMD1 (an identified STMD) to the visual presentation of targets embedded within cluttered, natural scenes. We examine CSTMD1 response changes to target contrast, as well as a range of target and background velocities. We find that background motion affects CSTMD1 responses via the competitive selection between features within the natural scene. Here, robust discrimination of our artificially embedded "target" is limited to scenarios when its velocity is matched to, or greater than, the background velocity. Additionally, the background's direction of motion affects discriminability, though not in the manner observed in STMDs of other flying insects. Our results highlight that CSTMD1's competitive responses are to those features best matched to the neuron's underlying spatiotemporal tuning, whether from the embedded target or other features in the background clutter. In many scenarios, CSTMD1 responds robustly to targets moving through cluttered scenes. However, whether this neuronal system could underlie the task of competitively selecting slow moving prey against fast-moving backgrounds remains an open question.

Description of Microgomphus farrelli sp. nov. (Odonata: Anisoptera: Gomphidae) based on adults of both sexes and larvae from Northern Thailand.

The new gomphid species, Microgomphus farrelli sp. nov., is described and illustrated on the basis of male and female adult specimens and larvae collected from Chiang Mai and Mae Hong Son province, Northern Thailand. It is compared with other species of the genus. Based on the larvae this species is most closely related to Microgomphus svihleri (Asahina, 1970), comb. nov., which is the senior and valid synonym of Microgomphus thailandicus Asahina, 1981, syn. nov.

Updated information on genus Gomphidictinus (Odonata: Gomphidae) in China with description of Gomphidictinus tongi sp. nov.

A new gomphid species, named as Gomphidictinus tongi sp. nov. (Holotype male, Mt. Diaoluoshan, altitude 930m a.s.l., Lingshui County, Hainan Province, China) is described here. It is regarded as the third species of Gomphidictinus based on the presence of the basal spine on median segment of the penis organ. Gomphidia interruptistria Zha, Zhang & Zheng, 2005 is regarded as a junior synonym of Gomphidictinus perakensis (Laidlaw, 1902), which is recorded from Yunnan, China.

A new species of the genus Burmagomphus Williamson (Odonata: Gomphidae) from Northern Thailand.

Burmagomphus chiangmaiensis sp. nov. (holotype: Ban Luang, Chom Thong, Chiang Mai province, Thailand, 890-900 m, 14 v 2012) is described and illustrated. It can be differentiated from its most similar congener, B. apricus from China, by shape of posterior hamulus, yellow trapezoid band on occiput, and larger size.

The head morphology of Pyrrhosoma nymphula larvae (Odonata: Zygoptera) focusing on functional aspects of the mouthparts.

BACKGROUND: The understanding of concerted movements and its underlying biomechanics is often complex and elusive. Functional principles and hypothetical functions of these complex movements can provide a solid basis for biomechanical experiments and modelling. Here a description of the cephalic anatomy of Pyrrhosoma nymphula (Zygoptera, Coenagrionidae) focusing on functional aspects of the mouthparts using micro computed tomography (µCT) is presented. RESULTS: We compared six different instars of the damselfly P. nymphula as well as one instar of the dragonfly Aeshna cyanea and Epiophlebia superstes each. In total 42 head muscles were described with only minor differences of the attachment points between the examined species and the absence of antennal muscle M. scapopedicellaris medialis (0an7) in Epiophlebia as a probable apomorphy of this group. Furthermore, the ontogenetic differences between the six larval instars are minor; the only considerable finding is the change of M. submentopraementalis (0la8), which is dichotomous in the early instars (I1,I2 and I3) with a second point of origin at the postero-lateral base of the submentum. This dichotomy is not present in any of the older instars studied (I6, middle-late and pen-ultimate). CONCLUSION: However, the main focus of the study herein, is to use these detailed morphological descriptions as basis for hypothetic functional models of the odonatan mouthparts. We present blueprint like description of the mouthparts and their musculature, highlighting the caused direction of motion for every single muscle. This data will help to elucidate the complex concerted movements of the mouthparts and will contribute to the understanding of its biomechanics not in Odonata only.