Monotomidae
Diagnosis
Monotomidae adults can be seperated from other small brown beetles using the following combination of characters (Sen Gupta 1988; Bousquet 2002a; Bousquet 2009; McElrath et al. 2012):
- generally narrow-elongate
- head prognathous, not concealed
- elytra distinctly truncate at apex, exposing at least one (females) or two (males) abdominal segments
- antennae short, stout, appearing 10-segmented (antennomere 10 and 11 fused) with a one or two segmented club formed from antennomeres 9 and/or 10+11
- tarsal formula 5-5-5 in females and 5-5-4 in males (see here) to tell the difference between monotomid males and females
- abdomen with 5 ventrites (small 6th genital capsule segment present in males) (Figure)
- ventrites 1 & 5 elongate, 2-4 comparatively short, subequal (Figure)
- procoxae rounded with hidden trochantins and with obliterated notosternal suture (Monotominae) (Figure) or procoxae somewhat transverse with partly exposed trochantins and typical notosternal suture (Rhizophaginae) (Figure)
- proxocal cavities broadly closed externally
Eliminate others
If the beetle you are identifying has any of the following features, it is NOT a Monotomid:
- 11 antennomeres (11th not fused with 10th) (see Smicripidae below)
- 3 club segments (see Smicripidae or Nitidulidae below)
- elytra completely covering abdominal segments from above (see Bostrichidae)
- ventrites subequal
- open procoxal cavities
Non-Monotomidae Look-alike Examples (not comprehensive)
Suggested References
Bousquet 2002a - diagnosis of family in North America, brief discussion of genera
Bousquet 2010 - diagnosis of family worldwide, review of biology of family
Sen Gupta 1988 - review of morphology of family and comparison to other beetle families
