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#WednesdaysWeeklyWeevil (1) – Systenotelus carludovicae

You knew it was coming – a new, weevil-centric natural history and taxonomy series: Wednesday’s Weekly Weevil. Twitter hashtag: #WednesdaysWeeklyWeevilAuthors will rotate. Systenotelus carludovicae is starting off the series.


Systenotelus carludovicae

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Systenotelus carludovicae, male in lateral view.

Link to SCAN occurrence record

Natural history. Systenotelus carludovicae, the “Panama Hat Palm Seed Weevil” (hereby named), is a highly specialized, seed feeding weevil that occurs only on select species of Panama Hat Palms (genus Carludovica; Cyclanthaceae) in Costa Rica and Panama. These weevils are significantly larger than close relatives, and the females in particular are tapered at both ends (rostrum and abdomen). This feature allows them to lay eggs into small inter-floral entrances “from the outside”. The larvae feed on multiple seeds. As a result, this species is fairly detrimental to its host – it is not a pollinator and further reduces the plant’s reproductive success by destroying fertilized seeds. There is an interesting morphological “arms race” among several species of Carludovica and Systenotelus, documented in detail in Franz (2004). The weevil species are successively longer and narrower, whereas the plant species have increasingly better protected female flowers. One might argue that Systenotelus “caused” the diversification of Carludovica species in southern Central America.

Other comments & fun facts. Systenotelus is Greek for “tapered at both ends” – a very fitting and beautiful name. The female flowers of the host plant species Carludovica sulcata are apparently so well protected against oviposition and seed feeding by Systenotelus weevils (who are not visitors of this species) that they are also hard to access for more beneficial, pollinating species of acalyptine weevils. A short video of a related species is posted here.

 


Systematics Section

Taxonomic name. Systenotelus carludovicae Anderson & Gómez-P. 1996: 890

Classification. Curculionoidea: Curculionidae: Curculioninae: Acalyptini Thomson 1859

Reference. Bouchard et al. 2011. Family-group names in Coleoptera (Insecta). ZooKeys 88: 1-972. Link

Common name. “Panama Hat Palm Seed Weevil” (hereby coined).

Relevant taxonomic treatment. Anderson & Gómez-P. 1996. Systenotelus, a remarkable new genus of weevil (Coleoptera: Curculionidae) associated with Carludovica (Cyclanthaceae) in Costa Rica and Panamá. Revista de Biología Tropical 45: 887-904. Link

Diagnosis (Anderson & Gómez-P. 1996). Species of Systenotelus are recognized easily by their relatively large body size (4.9-12.4 mm) for Derelomini [now: Acalyptini], pale to dark yellow color with various black dorsal and lateral maculations and general dorsal habitus. They are recognized further by the tumescent mesosternal process, tapered apex of the abdomen and associated very elongate-narrow genitalia in females, and by the form of the female pygydium which in dorsal view is constricted at the midlength. […] Pronotum longer than wide (l/w=1.12-1.15 in male; 1.42-1.46 in female). Rostrum relatively long (0.77-0.78 times the length of pronotum in male; 0.96-1.04 times the length of the pronotum in female). Each femur of male and middle and hind femora of female with large subapical blunt angulation. Abdominal sternum V of female long and narrow, much longer than wide; about as long as sterna I and II combined. Elytra of female in dorsal view with posterior one-half tapered to narrow apex. Aedeagus in dorsal view with margins uniform, not sinuate.

Phylogenetic treatment. Franz. 2006. Towards a phylogenetic system of derelomine flower weevils (Coleoptera: Curculionidae). Systematic Entomology 31: 220-287. Link

Additional references.

  • Franz. 2004. Analysing the history of the derelomine flower weevil-Carludovica association (Coleoptera: Curculionidae; Cyclanthaceae). Biological Journal of the Linnean Society 81: 483-517. Link
  • Franz & Valente. 2005. Evolutionary trends in derelomine flower weevils: from associations to homology. Invertebrate Systematics 19: 499-530. Link
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