Practice Quiz Answers: Dicyrtomina ornata versus Dicyrtomina saundersi

This is a difficult species pair to separate and they are frequently confused. Try answering the following questions:

Photo 1:


Q1a) Is this Dicyrtomina ornata or Dicyrtomina saundersi?
Answer: Dicyrtomina ornata.

Q1b) Explain your reasoning - what features lead you to your conclusion?

• Very short fourth antennal segment so this is Dicyrtomina.
• Strong dorsal (in addition to lateral) abdominal pigmentation - the line along the back (c.f. Dicyrtomina saundersi below).
• Dark blob of pigment rather than multi-barred cross on rear of apdomen. This is not reliable on its own - specimens of Dicyrtomina ornata and Dicyrtomina saundersi grade into each other. 
• Gradual but no sharp colour change along the length of the antennae.
• Dorsal colour of the 6th abdominal segment (the dorsal anal valve) is dark (difficult to see clearly in this photo but it's there).
• The identification is not based on a single feature but on the most probable outcome of the combination of all of them.

Photo 2:


Q2a) Is this Dicyrtomina ornata or Dicyrtomina saundersi?
Answer: Dicyrtomina saundersi.
Q2b) Explain your reasoning - what features lead you to your conclusion?

• Very short fourth antennal segment so this is Dicyrtomina.
• Multi-barred cross pattern on rear of abdomen. This is not reliable on its own - specimens of Dicyrtomina ornata and Dicyrtomina saundersi grade into each other. 
• Sharp colour change (yellow band) at ant2 / ant3.
• Dorsal colour of the 6th abdominal segment (the dorsal anal valve) is (predominantly) pale (c.f. Dicyrtomina ornata above).
• The identification is not based on a single feature but on the most probable outcome of the combination of all of them.

Photo 3:


Q3a) Is this Dicyrtomina ornata or Dicyrtomina saundersi?
Answer: Dicyrtomina saundersi.
Q3b) Explain your reasoning - what features lead you to your conclusion?

• Very short fourth antennal segment so this is Dicyrtomina.
• Multi-barred cross pattern on rear of abdomen. This is not reliable on its own - specimens of Dicyrtomina ornata and Dicyrtomina saundersi grade into each other. 
• Sharp colour change (yellow band) at ant2 / ant3.
• Dorsal colour of the 6th abdominal segment (the dorsal anal valve) is pale (c.f. Dicyrtomina ornata above).
• This is a juvenile specimen, these tend to be paler than adult Dicyrtomina saundersi (above).
• The identification is not based on a single feature but on the most probable outcome of the combination of all of them.