Protocorynus O’Brien, 2015

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 : 12-13

Protocorynus O’Brien and Tang, new genus

Type species: Protocorynus bontai O’Brien and Tang, new species

DIAGNOSIS: Pronotum dark orange with a median black macula at base, sometimes extending to anterior margin; pronotal width relative to pronotal length 1.35–1.65 in males and 1.60–1.74 in females; penis strongly flattened dorsoventrally; apical plate of tegmen with apical visor strongly curved transversely to form 3/4 circle; wing with 1A1 vein present and shorter than 1A2; wing rm vein sclerotized and forming one continuous vein with Mr vein.

DESCRIPTION. Body medium-sized to large (BL 3.4–5.2 mm); very robust, elongate broad-oval; dorsal surface bicolored dark orange to black, with portion of elytra and median area of pronotum partially black and other parts of body shades of orange-brown.

Male. Rostrum: coarsely punctate, 1.01–1.19 X longer than pronotum (n = 17); labial palps 3-segmented. Head: without postocular transverse groove. Antennae: insertion facing ventrad; scape length 1.34–1.54 X eye length and 1.39–1.67 X length of desmomeres 1+ 2 (n = 5), rhopalomeres 1 and 2 each with one curved elongate pit on distal surface rimming each side (visible at 40X magnification; Fig. 101), pit width ~ or <diameter of socket of terminal rhopalomere. Eyes: dorsal interocular distance /head width at eye 0.37–0.42 X; postocular head width 0.90–0.93 X head width at eye (n = 10). Prothorax: with sharply impressed line parallel to anterior margin of pronotum, forming distinct thickened, sclerotized anterior collar; anterior margin fringed with fine hairs; pronotal width/pronotal length (PW/PL) 1.45–1.65 (n = 17); notopleural sutures short and not reaching anterior edge of prosternum; distance between anterior margin of procoxae and anterior margin of prosternum 2.0–4.2 (mean = 3.4) X distance between posterior margin of procoxae and posterior margin of prosternum; sclerotized, black septum completely separating procoxal cavities; pronotum and dorsal surface of head and profemora without fine reticulation visible under high magnification (40–100X). Legs: profemora without spines, pegs or granulations on ventral surface; not asymmetrically swollen. Wings: four anal veins present, 1A1 obsolete and reaching only short distance beyond margin, 1A2 and 2A longer, 3A nearly reaching margin; rm vein sclerotized, posterior end forming one continuous vein with Mr vein and confluence forming 60˚ angle (Fig. 97).

Female. Same as male except: Rostrum: 1.55–1.76 X longer than pronotum (n = 11), on average 53% greater than in males. Eyes: postocular head width 0.94–1.03 X head width at eye (n = 10). Pronotum: PW/PL 1.61–1.74 (n = 10), on average 7 % greater than in males.

Genitalia and Associated Structures— Male. Length of penis and apodemes together 1.53–1.56 mm (n = 3). Penis: pedon strongly dorsoventrally flattened (Figs. 125–126), folding sharply at sides and continuing onto dorsal surface forming two parallel sclerotized folds along length except for apex, sides parallel except near apex, width (except near apex) 0.14 mm, apex in dorsal view (Fig. 173) widening distally from juncture with rest of penis to orifice, then narrowed, sides evenly rounded, convex, 0.17 mm at widest point, tip protruding into rounded point, orifice visible as longitudinal slit on membranous surface, or indiscernible; usually no dorsal sclerotized transverse bridge visible at junction with apodemes; apodemes 0.60 X as long as penis, in lateral view widening from junction with penis basad for 1/4 of length, then of equal width for 3/4 of length until rounded at base, bent ventrally from midpoint to base. Internal sac: membranous with spicules on distal portion, no other sclerotized structures visible, in retracted position protruding slightly from base between apodemes. Tegmen: apical plate in dorsal view (Figs. 197, 213) about twice as long as wide, rigid without ability to curl ventrally along longitudinal axis, sides subparallel until flaring at apical, visor-like structure, latter strongly curved transversely to form approximately 3/4 circle, apical margin broadly rounded in dorsal view, fringed along dorsal and lateral margins by numerous (> 30) setae, latter <20 % as wide as apical plate, setae along ventral margin of visor> 20 % as wide as apical plate; manubrium connecting with dorsal arch relatively far from own junction with apical plate, at ~ 1/4 length from distal end of manubrium; dorsal arch extending underneath apical plate nearly to apex of apical plate, apical edge fringed with filaments or setae appearing continuous with setae of apical plate visor, ventral surface with spicules, especially in basal section. Female. Sternite VIII: 1.20–1.26 mm long (n = 3), arms ~ as long as apodeme, diverging from apodeme with gradually increasing angle between arms for ~ 3/5 of length to a maximum angle of 50˚, then curving inward but without sharp angulate bend, then converging in final 3/10 of length, apices not touching; length of apical band of setae <maximum width between arms (Fig. 240). Spermathecal tube: not flattened, coiled or twisted, external surface covered with fine filaments, length <half length of apodeme of sternite VIII.

Etymological Note— The name of the genus is masculine and latinized from the Greek words protos (first) and koryne (club), indicating its position as the phylogenetically most basal genus of Allocorynina known to us.

Remarks— As here delimited this genus corresponds to the “ Honduras ” species group of Tang & O’Brien (2012). Morphology of the genitalia and molecular analysis of the 16S rRNA mitochondrial gene ( Tang et al. in prep.) indicate that this genus is the most distinct and basal of the Allocorynina . It’s only known host is a species of Dioon restricted to Honduras within the Chortis Block. The Chortis Block is a continental fragment of land that has moved gradually eastward from a position during the Cretaceous on the western side of Mexico to its present position southeast of the Yucatan Peninsula. It has been partly isolated from the rest of Mesoamerica by seaways and mountains during this time period ( Coates, 1997). The Chortis Block is a candidate for the geographic origin of the extant Allocorynina inhabiting New World cycads and the genus Dioon is likely the original host lineage.

Host and Geographic Distribution— Known only from one cycad species, Dioon mejiae , which is confined to Honduras, ca. 700 km east of the next-closest species of Dioon in Mexico ( Haynes & Bonta, 2007).