Cotithene stratiotricha Franz

Franz, Nico M., 2008, Revision, phylogeny and natural history of Cotithene Vo s s (Coleoptera: Curculionidae), Zootaxa 1782, pp. 1-33 : 9-12

Cotithene stratiotricha Franz , sp. n.

Diagnosis. Length 2.7–3.3 mm; rostrum in male ( Figs. 3 , 5 B) in lateral view expanded near basal 2/5, slightly angulate, head ( Figs. 3 , 5 B) with convex elevation, three triangular projections and dense, short to long, suberect setae, length of setae apparently positively allometric, pronotum ( Figs. 2 A, 2B) slightly convex, aedeagus ( Fig. 9 B) in lateral view apically strongly deflexed, internal sac with paired, undulate, obliquely orientated sclerites; procoxal cavities in female very narrowly separated, sternum VIII ( Fig. 9 B) with furcal arms U-shaped, spermatheca ( Fig. 9 B) J-shaped, with small, narrowly convex projection on outer margin near point of deflection. Cotithene stratiotricha may be distinguished from all species of the leptorhamphis-melanoptera clade by its relatively small size and more basal expansion of the rostrum in the male. Larger males differ from those of C. dicranopygia by several modifications on the head, whereas smaller males and females are distinguished from C. dicranopygia by the particularities of the terminalia. Males of C. stratiotricha are remarkably variable with respect to the angulate expansion, sculptures and setation of the rostrum and particularly the head. In the smallest males ( Fig. 3 A) these features are nearly indistinct, whereas the largest males ( Figs. 3 C, 3D) have conspicuous triangular projections and very long, suberect setae that are densely arranged in a patch on the frons and directed anterodorsad. Large males are also characterized by a larger and more globular pronotum. In summary, C. stratiotricha presents a series of autapomorphic transformations, many of which are possibly related to alternative reproductive strategies in the males.

Description. Male. Length 2.8–3.3 mm, width 1.0– 1.2 mm, elongate, l/w = 2.7–2.8 (N = 5). Color light reddish-brown, rostrum and head darker, reddish-brown, legs yellowish-brown, elytra darker, brown. Rostrum ( Figs. 3 & 5 B) 0.6–0.7 mm, short, r/p = 0.5–0.6; dorsally arcuate, angulate-tumescent near basal 2/5; broad, apically slightly narrowed; dorsal impression indistinct; antennal insertion at apical 1/3 to 2/5. Head ( Figs. 3 & 5 B) dorsally with distinct, irregular elevation, with 3 small to large, medially directed, triangular projections: 2 lateral (near dorsal margin of each eye) + 1 posterior; with dense, very long, suberect, aurate setae directed anterodorsad, longest setae nearly half as long as height of eye, increasing in length towards middle, intraspecifically variable, apparently positively allometric. Pronotum ( Figs. 2 A & 2B) slightly convex, anterolaterally not impressed. Proventrite 2x as long as mesoventrite, without anterolateral impressions or tumescences; procoxal cavities separated by slightly less than width of antennal club. Elytra ( Figs. 2 A, 2B) posteriorly not attenuate; anterior elevation indistinct; striae slightly broader than intervals. Spiculum gastrale slightly shorter than aedeagus; furcal arms slightly arcuate, curving outward. Aedeagus ( Fig. 9 B) l/w = 3.6– 3.8 (N = 3), widest near middle, gradually narrowing in apical half, apex acutely projected, strongly deflexed by nearly 90°; internally with small, paired, explanate, obliquely orientated sclerites; sclerites subparallel yet asymmetrical, margins irregular, undulate, apically narrowed; apodemes of similar length as body.

Female. Length 2.7–3.0 mm, width 1.1–1.2, l/w = 2.5–2.6 (N = 5). Color more homogeneously (light) reddish-brown. Rostrum ( Figs. 2 C, 2D) 0.8–0.9 mm, r/p = 0.9–1.0; narrow, width similar throughout; antennal insertion near middle. Head ( Figs. 2 C, 2D) without elevation, tumescences and modified long setae as present in male. Pronotum ( Figs. 2 C, 2D) less expanded. Procoxal cavities very narrowly separated. Elytra ( Figs. 2 C, 2D) as in male. Sternum VIII ( Fig. 9 B) posteriorly U-shaped, furcal arms slightly arcuate, apices with 8–10 setae. Spermatheca ( Fig. 9 B) J-shaped, outer margin near point of deflection with small, narrowly convex projection, orientated in parallel with basal half of spermatheca, apex very small, acuminate, slightly deflected.

Material examined. Holotype male " Costa Rica, Heredia, La Selva Biol. Stat. (OTS), N 10°26', W 83°59', 40 m, on Dicranopygium wedelii , leg. N. Franz, VI-16-2001 " ( MUCR); male paratypes, same label data as holotype ( CMNC, 5; CWOB, 5; DEIC, 5; INBC, 5; MIUP, 5; MIZA, 5; MUCR, 5; NMFC, 5; NMNH, 5), " Costa Rica, Heredia, La Selva Biol. Stat. (OTS), N 10°26', W 83°59', 40 m, on Dicranopygium wedelii , leg. N. Franz, VI-18-2001 " ( UPRM, 5), " Costa Rica, Heredia, INBio Farm, near Guápiles, N 10°10', W 83°48', 250 m, on Asplundia microphylla, R.S. Anderson , VI-24-2000 " ( CMNC, 10); female paratypes, same label data as holotype ( CMNC, 5; CWOB, 5; DEIC, 5; INBC, 5; MIUP, 5; MIZA, 5); " Costa Rica, Heredia, La Selva Biol. Stat. (OTS), N 10°26', W 83°59', 40 m, on Dicranopygium wedelii , leg. N. Franz, VI-18-2001 " ( MUCR, 5; NMFC, 5; NMNH, 5), " Costa Rica, Heredia, La Selva Biol. Stat. (OTS), N 10°26', W 83°59', 40 m, on Dicranop. umbrophilum , leg. N. Franz, VII-29-1997 " ( UPRM, 5), " Costa Rica, Heredia, INBio Farm, near Guápiles, N 10°10', W 83°48', 250 m, on Asplundia microphylla, R.S. Anderson , VI-24-2000 " ( CMNC, 10).

Etymology. Named for the distinct pattern of setation on the head of the male, which resembles an army "crew cut"; from the Greek stratios (of an army) and trichos (hair).

Natural history. Cotithene stratiotricha has been collected in three localities in the Costa Rican Cordillera Central ( Fig. 13 A), i.e. La Selva, INBio Farm and also Refugio Nacional de Fauna Silvestre de Fauna Silvestre, Área de Conservación Toruguero, Provincia Limón. At La Selva, this species is associated with Dicranopygium umbrophilum and D. wedelii Harling , whereas the specimens from INBio Farm were taken on Asplundia microphylla (Oerst.) Harling. An extensive sampling effort of derelomine flower weevils visiting D. wedelii inflorescences at La Selva yielded no individuals of C. stratiotricha during the initial phase of pollinator attraction (N = 10 inflorescences) or during the terminal phase when the pollen is released (N = 10 inflorescences). However, during the intermediate phase 1.1±1.0 adults were present on the inflorescences (N = 41 inflorescences). These results indicate that C. stratiotricha does not function as a pollinator of D. wedelii at La Selva, since this would require a closer synchronization with the appearance of the receptive stigmata and pollen. Nevertheless, the adults can remain on an inflorescence for several hours while feeding on floral parts, mating and ovipositing into the central axis. The larvae are herbivorous and develop in the rachis, which may lead to infructescence abortion.

The variable setal patch on the head of the males represents an unusual case of positive allometry ( Fig. 3 ) and is most likely related to male-male conflicts for access to reproductively active females (see also Franz 2003a, 2007a, Franz & Valente 2005). However, repeated attempts to record the use of these structures were unsuccessful (Franz, personal observation).

Figures

FIGURE 2. Habitus of Cotithene stratiotricha. A, male, dorsal view; B, male, lateral view; C, female, dorsal view; D, female, lateral view.

FIGURE 3. Variation of rostrum and head in males of Cotithene stratiotricha. A, small male, lateral view; B, intermediate-sized male, lateral view; C, large male, lateral view; D, large male, dorsal view.

FIGURE 5. Rostrum and head of Cotithene males, lateral view. A, C. dicranopygia; B, C. stratiotricha.

FIGURE 9. Genital structures of Cotithene species, from left to right: aedeagus, ventral view; aedeagus, lateral view; posterior region of female sternum VIII, ventral view; spermatheca, lateral view; shaded areas depicting structures of the internal sac. A, C. dicranopygia; B, C. stratiotricha.

FIGURE 13. Reported localities of Cotithene in Costa Rica and Panama (A) and Venezuela (B). See text for further detail.