Hemistephanus

MATERIALS & METHODS

Specimens were obtained from all major museums in the world, and from collecting trips to the Amazon rainforest. A total of 265 specimens of Hemistephanus were studied, including all types.

Over 300 external morphological characters and 36 biometric ratios, derived from 39 different measurements for each specimen (~7800 measurements total) were investigated. Measurements are illustrated below.

Measurements evaluated for Hemistephanus

To the genus-level analysis, Schlettererius cinctipes, the most basal species in Stephanidae ², was used as out-group.

Species were interpreted in four consecutive steps:

• Literature analysis
• Qualitative investigation
• Biometric investigation
• A final integrated analysis

Methodological Problems

• The following problems, never before consistently considered for Stephanidae, were investigated:
  1. Revision, definition, and illustration of morphological terms
  2. Search for new characters
  3. Definition of the taxonomic weight of each character
  4. Relative importance of characters for male and female taxonomy
  5. Adequate observational techniques
  6. Taxonomic importance of biometric data
  7. Presentation and interpretation of biometric data.

• The weight of each biometric rate was independently evaluated for males and females, according to:
  1. Their power in isolating couples of closely related species
  2. Their power in grouping related species
  3. Degree of difficulty and precision in taking the measurements to calculate the rate.

Biometric data presentation

Biometric ratios were most efficiently compared in graphics like the one below. Each bar represents one specimen, so that measurements of all specimens appear on each graph.

The following construction is simple, direct (no transformations involved), and comprehensive (all specimens of all species visualized at once).

Ratio Ov/Pt for all species and specimens.

Observational Techniques - Illumination

Fluorescent illumination was especially useful for observing microsculpture patterns. Its intense emission of high energy waves allows a much greater definition than that provided by incandescent lights ¹⁴. Light diffusors can eliminate the glare of incandescent lights, but they can be clumsy to use with the usually large and delicate Stephanidae, increasing the risk of accidents with the specimens.

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This page last updated: November 21, 1997.