Rhopalotria Chevrolat, 1878

O’Brien, Charles W. & Tang, William, 2015, Revision of the New World cycad weevils of the subtribe Allocorynina, with description of two new genera and three new subgenera (Coleoptera: Belidae: Oxycoryninae), Zootaxa 3970 (1), pp. 1-87 : 21-23

Rhopalotria Chevrolat, 1878

Type species: Rhopalotria dimidiata Chevrolat, 1878 , by monotypy.

DIAGNOSIS. Rhopalotria can be distinguished from other Allocorynina by the following combination of diagnostic characters: ventrodistal surface of profemora in males with one or two spines which border the base of the apical pit that receives the tibia in repose and no other associated teeth, pegs or fields of granules; notopleural suture extended anteriad near prosternal margin; penis with apex broadly rounded (subtruncate); tegmen with apical visor that is relatively flat, not stongly tranversely curved; wing with vein 1A1 missing, 1A2 & 2A present and 3A obsolete beyond its confluence with 2A or not reaching margin.

REDESCRIPTION. Body minute to medium-sized (BL = 1.8–3.6 mm, mean = 2.6 mm, n = 170); robust, broad-oval; uniformly pale tan to brownish or distinctly bicolored black and orange-brown.

Male. Rostrum: rugose to denticulate on dorsal and dorsolateral surface, degree of denticulation increased with size of individual; 0.91–1.23 X as long as pronotum (n = 58); labial palps 2-segmented. Head: lacking postocular transverse groove. Antennae: with insertion facing ventrad; scape length = 0.73–1.13 X eye length and 0.76–1.45 X length of desmomere 1+2 (n = 34); club with rhopalomeres 1 and 2 each with both sides of distal surfaces with 2–3 pits each (visible at 112.5X magnification), if 3 then pits round (Figs. 109–112), if 2 then pits often fused or partially divided forming elongate pits of irregular outline (Figs. 106–108); width of antennal club pits <diameter of socket for terminal rhopalomere. Eyes: dorsal interocular distance relative to head width at eye = 0.28–0.52; postocular head width generally shorter than head width at eye (mean = 0.97, range = 0.91–1.05, n =71). Prothorax: lacking impressed line paralleling anterior margin of pronotum; no distinct thickened sclerotized anterior collar, marginal region smooth and gradually thinning toward edge; fine hairs fringing anterior margin of prothorax visible at 40–112.5X magnification, but obsolete or possibly worn off on dorsum in area bounded by eyes (except in R. vovidesi ), bases of fine hairs appearing present under pronotal margin, but not emerging onto surface; notopleural suture reaching or nearly reaching anterior margin of prosternum; pronotal width/pronotal length (PW/PL) = 1.34–1.58 (n = 62); sclerotized, black-colored septum completely separating procoxal cavities; individuals of most species with pronotum, dorsal surface of head and forefemora with fine reticulation visible under high magnification 40–100X, but reticulation completely absent in one species ( R. vovidesi ); distance from anterior margin of procoxae to anterior margin of prosternum on average 2.2–2.9 (except in R. vovidesi = 1.2) X distance from posterior margin of procoxae to posterior margin of prosternum. Legs: profemora asymmetrically swollen, with single spine or pair of spines bordering base of apical pit receiving tibia in repose on ventral apex of profemora in major males. Wings: venation reduced (Fig. 99) with 1A1 missing, 1A2 reaching only short distance beyond margin, 2A complete, 3A obsolete beyond its confluence with 2A or reaching up to halfway to margin; rm vein not sclerotized, forming T-junction with Mr vein, most of length of Mr vein occurring distad of junction.

Female. Same as male except: Rostrum: 1.22–1.79 X longer than pronotum (n = 60), 13.5–42.2% greater in females (13.5–18.2% in subgenus Rhopalotria and 26.8–42.2% insubgenus Allocorynus ) than in males and never with overlap between sexes within species; as in males, female individuals of most species with head, prothorax and profemora with fine reticulation, except for the rostrum, which is always smooth in females. Antennae: scape length/eye length = 0.75–1.23 (n = 34), 5.2–15.2% greater than in males with some overlap between sexes within species; scape length/length of desmomere 1+2 together = 0.86–1.45 (n = 34), 1.7–12.4% greater than in males with some overlap between sexes within species. Eyes: dorsal interocular distance relative to head width at eye = 0.28–0.52; postocular head width/head width at eye greater than in males for each species (mean = 1.05, range = 0.97–1.16, n =58). Prothorax: with pronotal width/pronotal length (PW/PL) = 1.39–1.63 (n = 60); on average 3– 11% greater than in males, but typically with some overlap between sexes within species; distance from anterior margin of procoxae to anterior margin of prosternum on average 2.0–2.9 (except in R. vovidesi = 0.9 and R. calonjei = 1.6) X distance from posterior margin of procoxae to posterior margin of prosternum.

Genitalia and Associated Structures— Male. Length of penis and apodemes together 0.68–0.90 mm (n = 19), shortest within Allocorynina . Penis: trough-shaped, in dorsal view sides converging slightly toward apex, apex broadly rounded to subtruncate, tectum appearing thin and unsclerotized, no transverse dorsal sclerotized bridge at junction of penis with apodemes; apodemes slightly longer than penis, in lateral view widening gradually basad until narrowing abruptly at rounded base (Figs. 135–148, 178–184). Internal sac: in retracted position with pair of sclerotized rods, one on each side of median axis, forming transfer apparatus located at junction of apodemes at base of penis. Tegmen: apical plate in dorsal view slightly narrowed to truncate apex, apex with dorsal shelf protruding distad and fringed with 9–20 setae (depending on species), setal length less than width of apical plate (Figs. 201–204, 218–224). Female. Sternite VIII: arms 0.5–1.0 X as long as apodeme, diverging evenly from apodeme, near midpoint curved inward without angulate bend, becoming subparallel, then converging slightly near apices; band of setae connecting apices of arms (Figs. 245–251). Spermathecal tube: coiled, texture relatively smooth without external filaments, uncoiled length <length of apodeme of sternite VIII.

Remarks —As here delimited this genus corresponds to the “dimidiata ” species group of Tang & O’Brien (2012). Herein we divide this genus into two subgenera based on morphology and molecular analysis of the 16S rRNA gene ( Tang et al. in prep.): 1) Nominate subgenus Rhopalotria consisting of the species R. dimidiata , R. meerowi and R. slossoni ; 2) Subgenus Allocorynus consisting of R. calonjei , R. furfuracea , R. mollis and R. vovidesi . Members of the subgenus Rhopalotria may be distinguished morphologically from the subgenus Allocorynus by number and arrangement of spines on the ventrodistal surface of the profemora of males, the number of pits on rhopalomeres 1–2 of the club, and the degree of sexual dimorphism in rostral length/pronotal length (RL/PL). In the subgenus Rhopalotria , the ventrodistal pit of the male profemora that receives the tibia is bounded by a spine on either side of the base (total of two spines; Fig. 274), whereas in the subgenus Allocorynus there is only a single spine at the base of the pit (Fig. 273). In the subgenus Allocorynus there are 3 pits on each side of rhopalomeres 1–2 of the club, the center one which is larger and usually partly covered with a spoke-like arrangement of filaments (Figs. 109–112), whereas in the subgenus Rhopalotria there are 2 pits on each side that are often fused or partially divided so that they are often of irregular shape and outline (Figs. 106–108). In the subgenus Rhopalotria RL /PL is 13.5–18.2% greater in females than in males, whereas in the subgenus Allocorynus it is 26.8–42.2% greater in females than in males. Herein we also recognize two species groups within the subgenus Allocorynus , a Mesoamerican group consisting of R. calonjei , R. furfuracea and R. mollis and a “spinulosum ” species group consisting of R. vovidesi . The “spinulosum ” species group can be distinguished from the former by the presence of long hairs on the scutellum and the absence of fine reticulation on the head and pronotum.

Host and Geographic Distribution— This is a northern lineage and members of this genus are known from one species of Dioon , D. spinulosum , in southern Mexico and from most, but not all species of Zamia that have been surveyed in Mexico, Belize, the Greater Antilles, the Bahamas and Florida, U.S.A. Rhopalotria has not yet been collected south of Belize. All specimens of Allocorynina from Costa Rica, Panama and South America, tentatively placed in Rhopalotria by Tang & O’Brien (2012), are assigned to the genus Notorhopalotria in this paper. The larvae of Rhopalotria have been extracted from the male cones of Z. furfuracea , Z. loddigesii , Z. paucijuga , Z. spartea , Z. integrifolia and other members of the Z. pumila complex in Cuba, Florida, Jamaica and the Bahamas ( Muñiz & Barrera 1969, Norstog & Fawcett 1989, Tang 1987, unpub. data).

Subgenus Rhopalotria Chevrolat, 1878

Type species: Rhopalotria dimidiata Chevrolat, 1878 , by monotypy.

DIAGNOSIS. The nominate subgenus Rhopalotria can be distinguished from all other Allocorynina by the following combination of characters: 2 deep pits on either side of rhopalomeres 1 and 2 of the club that are often fused or partially divided so that they are typically of irregular outline (Figs. 106–108); ventrodistal surface of male profemora with a pair of spines that brackets and borders the base of the apical pit that receives the tibia in repose (Fig. 274).

DESCRIPTION. Body minute to medium-sized (BL = 1.8–3.2 mm, mean = 2.6 mm, n = 112); robust, broad-oval; dorsal surface bicolored orange to black, elytra completely black or black with portion of base brown.

Male. Rostrum: 1.05–1.21 X longer than pronotum (n = 37). Antennae: scape length = 0.75–0.96 X eye length and 0.76–1.03 X length of desmomeres 1+2 (n = 15); club with rhopalomeres 1 and 2 with both sides of distal surfaces with 2 pits each, pits often fused or partially divided to form elongate pits of irregular outline (Figs. 106–108). Prothorax: pronotal width/pronotal length (PW/PL) = 1.36–1.58 (n = 29); distance from anterior margin of procoxae to anterior margin of prosternum on average 2.2–2.9 X distance from posterior margin of procoxae to posterior margin of prosternum. Legs: ventrodistal surface of profemora with pair of spines bracketing and bordering base of apical pit receiving tibia in repose (Fig. 274).

Female. Same as male except: Rostrum: 1.22–1.57 X longer than pronotum (n = 29), on average 13.5–18.2% greater in females than in males and never with overlap with males within species. Antennae: scape length = 0.83– 1.12 X eye length (n = 15). Prothorax: PW/PL = 1.45–1.61 (n = 29), on average 3–8% greater than in males, with no overlap or broad overlap between sexes depending on species.

Genitalia and Associated Structures— Male. Length of penis and apodemes together 0.68–0.84 mm (n = 8). Penis: (Figs. 135–140, 178–180). Tegmen: apical visor 6–15% length of apical plate (Figs. 201–202, 218–220). Female. Sternite VIII: (Figs. 245–247) 0.56–0.75 mm long (n = 9), arms ~ 0.5–0.7 X as long as apodeme.

Host and Geographic Distribution— This subgenus is restricted to Florida, U.S.A., six islands in the Bahamas (Abaco, Andros, Eleuthera, Grand Bahama, Long Island and New Providence) and portions of the Greater Antilles ( Cuba, Isle of Youth, Cayman Islands and Jamaica). Its hosts are limited to the members of the Zamia pumila complex ( Eckenwalder 1980). Larvae develop singly in individual sporophylls of male cones in all three species of this subgenus ( Norstog et al. 1992, Tang 1987, unpub. obs.).