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Meruidae Spangler and Steiner 2005

Meru phyllisae Spangler and Steiner 2005

Warren Steiner, Alex Wild, and Andrew Short
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Containing group: Adephaga

Introduction

Meru phyllisae is among the world's smallest and rarest beetles. Less than a millimeter in length, M. phyllisae is known only from the El Tobogan de la Selva cascade in Amazonian Venezuela. There, specimens have been collected clinging to vegetative debris submerged in the stream.

As in other crawling aquatic Adephaga, Meru has a hydrodynamic teardrop shape. The feeding habits of Meru are not known, but lab observations and mouthpart morphology suggest that it may graze on algal filaments or fungal hyphae (Spangler & Steiner 2005). Intriguingly, the population at El Tobogan is dimorphic in wing morphology. Most individuals are brachypterous and flightless but a few have fully developed flight wings, suggesting adaptation to temporary pools or flooding.

The single species is placed in its own family, Meruidae, in the suborder Adephaga. Meruidae is among the newest beetle families, discovered in the 1980s and formally described in 2005 (Spangler & Steiner 2005).

Characteristics

The following diagnosis for the adults is modified from Spangler & Steiner (2005):

  1. Size small, total length less than 1 millimeter.
  2. Body sculpture rough, and integument covered with flat, wrinkled setae.
  3. Tarsal claws pectinate.
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    Click on an image to view larger version & data in a new window

    Meru phyllisae. ©

  4. Tibial spurs tridentate (inner metatibial spur serrate).
  5. Labrum with pairs of overlapping spatulate setae.
  6. Legs without swimming hairs.
  7. Scapus small and rounded.
  8. Antennal flagellum with segments alternately large and small.
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    Click on an image to view larger version & data in a new window

    Meru phyllisae. ©

  9. In spite of efforts to rear Meru in the laboratory (Spangler & Steiner 2005), immature forms are unknown.

Discussion of Phylogenetic Relationships

The small size and corresponding reduction of morphological characters complicates the placement of Meru within Adephaga. Nonetheless, the first morphological (Beutel et al 2006) and molecular (Balke et al 2008) phylogenies both infer a sister relationship between Meru and Noteridae, the burrowing water beetles.

Other Names for Meru phyllisae Spangler and Steiner 2005

References

Balke, M., I. Ribera, R. Beutel, A. Viloria, M. Garcia, and A.P. Vogler. 2008. Systematic placement of the recently discovered beetle family Meruidae (Coleoptera: Dytiscoidea) based on molecular data. Zoologica Scripta, 37: 647-650. doi: 10.1111/j.1463-6409.2008.00345.x

Beutel, R.G., M. Balke, and W.E. Steiner. 2006. The systematic position of Meruidae (Coleoptera, Adephaga) and the phylogeny of the smaller aquatic adephagan beetle families. Cladistics, 22: 102-131. doi:10.1111/j.1096-0031.2006.00092.x

Spangler, P.J. and W.E. Steiner. 2005. A new aquatic beetle family, Meruidae, from Venezuela (Coleoptera: Adephaga). Systematic Entomology, 29: 339-357.

Information on the Internet

Title Illustrations
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Click on an image to view larger version & data in a new window
Scientific Name Meru phyllisae
Specimen Condition Dead Specimen
Identified By Warren Steiner
Life Cycle Stage Adult
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Copyright ©
About This Page


Smithsonian National Museum of Natural History, Washington, D. C., USA

Alex Wild
University of Illinois, Urbana, Illinois, USA


Correspondence regarding this page should be directed to Warren Steiner at , Alex Wild at , and Andrew Short at

All Rights Reserved.

Citing this page:

Steiner, Warren, Alex Wild, and Andrew Short. 2010. Meruidae Spangler and Steiner 2005. Meru phyllisae Spangler and Steiner 2005. Version 16 August 2010. http://tolweb.org/Meru_phyllisae/29297/2010.08.16 in The Tree of Life Web Project, http://tolweb.org/

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