Monotoma testacea Motschulsky, 1845

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POLYPHAGA Emery, 1886

CUCUJOIDEA Latreille, 1802

MONOTOMIDAE Laporte, 1840

MONOTOMINAE Laporte, 1840

Monotoma Herbst,1793

Widespread and native to the Palaearctic region from Europe to the far east of Russia including North Africa and Asia Minor, this species is also synanthropic and has become established in the United States, Canada, South America and New Zealand. In Europe it occurs sporadically from the Mediterranean north to the UK and into southern Fennoscandia, and while it tends to be infrequently recorded in the wild but may be abundant under artificial conditions e.g. among stored grains in mills and granaries or among bone meal. The UK distribution includes Southeast and Central England, Anglesey and Wales although in the west it tends to occur mostly in coastal areas. Adults occur year-round both in the wild and under artificial conditions; they peak in the spring and again during October and November, and are generally most common from autumn until late winter. The natural habitat is among decaying vegetation in almost any situation, often in compost or manure but also among leaf litter in fens and marshes or in old straw bales or silage etc, they usually occur in numbers and often alongside other members of the genus such as M. bicolor Villa & Villa, 1835. The early stages and development have been described by Jaloszyński (2021). Briefly, several generations were raised under artificial conditions on baker’s yeast and individual females from two independent cultures, each accompanied by a single male, produced 57 and 94 eggs over their lifetimes and laid between 1 and 5 eggs per day. Developmental time from egg to adult took between 34 and 42 days; the first instars emerging after 5 or 6 days and moulting after 2 or 3 days, second instars took between 3 and 5 days, third instars between 2 and five days, an immobile prepupal stage lasted between 12 and 13 days and pupal development lasts between 7 and 10 days. Adults are rarely seen in the open and so should be searched for by sieving or extracting samples of compost or other likely material, and all specimens should be taken as they will need to be examined very carefully for certain identification.

Monotoma testacea 1

Monotoma testacea 1

© Lech Borowiec

1.6-2.2 mm. Elongate and rather narrow, body and appendages pale brown to yellowish-brown, dorsal surface with short and pale scale-like pubescence; mostly random on the head and pronotum and seriate on the elytra. Head quadrate or nearly so, broadest across convex and protruding eyes and with slightly diverging or parallel temples that are sharply angled with the weakly-curved basal margin, cheeks long and converging, vertex smoothly convex and frons with shallow impressions. Antennae 10-segmented with a large single-segmented club. Pronotum slightly elongate (1.1-1.2X longer than wide) with straight or slightly sinuate and parallel lateral margins, anterior angles protruding and rounded, posterior angles obtuse and weakly produced, basal and apical margins curved. Pronotal surface with distinct basal depressions and weak, indistinct impressions anteriorly, punctures wide, shallow and distinct, not confluent. Elytra evenly curved from rounded and slightly produced shoulders to separately-rounded apical margins which leave the pygidium exposed, surface with distinct rows of small punctures. Legs short and robust, with clavate femora and tibiae widened from the base to truncate apices with small but distinct spurs. Tarsi 5-5-4 in males, 5-segmented in females.