Parallocorynus Voss, 1943

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 : 34-37

Parallocorynus Voss, 1943

Type species: Allocorynus (Parallocorynus) bicolor Voss, 1943 , by monotypy.

DIAGNOSIS. The genus Parallocorynus can be distinguished from other Allocorynina by the following combination of diagnostic characters: head with postocular transverse groove; rhopalomeres 1–2 of club with both sides of distal ends each with single round to oval pit; RL/PL = 0.96–1.48 in males and 1.27–1.95 in females; males and females without fine reticulations visible on dorsum of head, pronotum and profemora at magnifications of 40– 100X; male penis with pronounced transverse dorsal sclerotized bridge at base; wing with 3–4 anal veins present, 1A 2 obsolete, short, occasionally missing; wing rm vein not sclerotized and forming T-junction with Mr vein.

REDESCRIPTION. Body small to large (BL = 2.5–6.2 mm, mean = 4.1 mm, n = 414); robust, elongate broad-oval; uniformly brown or dorsal surface bicolored orange to black, with portion of elytra often partially black and other parts of body and legs with same two colors.

Male. Rostrum: denticulate on dorsal and dorsolateral surface, degree of denticulation increased with increase in size of individual, 0.96–1.48 X as long as pronotum (n = 220); labial palps 3-segmented. Head: with strongly developed postocular transverse groove. Antennae: insertion facing anteriad; scape length = 1.11–2.61 X eye length (n = 57; mean for each species variable = 1.18–2.23) and 1.07–1.58 X length of funicle 1–2 together [n = 57; mean for 11 or 12 species similar = 1.21–1.39 (exception Parallocorynus chemnicki = 1.07, n=1)], rhopalomeres 1–2 of club with one large oval pit on distal surface on each side (visible with stereoscope at 40X magnification), each pit with numerous filaments along rim pointing to center (Figs. 113–124); width of antennal club pits>, ~ or <diameter of insertion for club apical rhopalomere (Figs. 113–124). Eyes: dorsal interocular distance relative to head width at eye = 0.40–0.56; postocular head width <or> head width at eye (mean = 0.99, range = 0.91–1.10, n = 108). Prothorax: with sharply impressed line paralleling anterior margin, forming distinct thickened, sclerotized anterior collar; fine hairs fringe anterior margin; pronotal width/pronotal length (PW/PL) = 1.11–1.47 (n = 236); notopleural suture short and not reaching anterior margin of prosternum; distance from anterior margin of procoxae to anterior margin of prosternum on average 2.6–5.6 X distance from posterior margin of procoxae to posterior margin of prosternum; sclerotized, black-colored septum completely separating procoxal cavities absent. Legs: profemora either: 1) swollen and with granulations on ventral surface, 2) swollen and with granulations and a spine on ventral surface or 3) not swollen and without granulations or spines. Wings: 3–4 anal veins, 1A 1 complete, 1A 2 obsolete and reaching only short distance from margin or occasionally missing, 2A complete, 3A obsolete and reaching halfway to margin beyond its confluence with 2A; rm vein not sclerotized, forming a T-junction with Mr vein, most of length of Mr vein occurring as proximal spur beyond junction (Fig. 98).

Female. Same as male except: Rostrum: 1.27–1.95X longer than pronotum (n = 187), on average 14–52% greater than in males, with no overlap between sexes within species. Eyes: postocular head width <or> head width at eye, 2.3–8.0% greater in females than males (mean = 1.04, range = 0.91–1.14, n = 102). Prothorax: PW/PL = 1.14–1.51 (n = 211), on average 2–17% greater than in males, with slight overlap between sexes within some species. Legs: profemora not swollen and differing from those of males only in subgenera with males having profemora with granulations or spines.

Genitalia and Associated Structures— Male. Length of penis and apodemes together 1.04–1.64 (1.76 in one specimen atypically straightened) mm (n = 46), reaching greatest length in Allocorynina . Penis: in lateral view longitudinally trough-shaped, moderately curved, in dorsal view sides subparallel or converging slightly apicad for most of length, slightly expanding laterally before apex at approximately 2/3 from base, or not (Figs. 149–172); apex narrowing apicad to rounded point; length from orifice to apex approximately 1 X or 2 X width at orifice (Figs. 185–196); transverse dorsal sclerotized bridge present at base; apodemes approximately same length as penis, slightly concave on inner surface, in lateral view widening gradually from junction with penis until narrowed at rounded base. Internal sac: in retracted position protruding well beyond base of penis almost to, or beyond, base of apodemes, basal section mostly covered by scales or spicules, with sinuate endophallic strut along ventral midline (Figs. 150, 152, 154, 156, 158, 160) or not (Figs. 162, 164, 166, 168, 170, 172), sclerotized endophallic dart visible usually within basal third–half. Tegmen: apical plate in lateral view <1/4 length of plate, in dorsal view slightly narrowed apicad to truncate or slightly rounded apex, apex without dorsal shelf, apical plate rigid except for distal margin, there curled ventrally along transverse axis, or not; fringed with setae numbering> 20–30 or <20 and with longest setae <width of apical plate (Figs. 205–212, 225–236). Female. Sternite VIII: (Figs. 252–263) 0.96–1.47 mm long (n = 35), arms ~ half as long as apodeme,diverging from apodeme at constant or slightly increasing angle between arms for 2/3–4/5 of length, then forming sharp angulate or rounded bend, then usually converging (apices not touching) but sometimes becoming subparallel; band of setae on slightly sclerotized membrane connecting apices of arms, when arms not under tension membrane between forming cradle, lateral margins of arms extending laterally as thin poorly sclerotized flap-like extensions, distal half of arms and lateral margins studded with protuberances; translucent tissue between arms and extending beyond lateral margins with shagreen-like texture. Spermathecal tube: coiled, flattened and expanded at base, texture relatively smooth without external filaments, uncoiled length <half length (subgenera Eocorynus , Neocorynus and Parallocorynus ) or> or = length (subgenus Dysicorynus ) of sternite VIII (Figs. 264–265).

Remarks— As here delimited this genus includes the “ bicolor ” and “edule ” species groups of Tang & O’Brien (2012). Herein we divide this genus into four subgenera based on morphology and molecular analysis of the 16S rRNA gene ( Tang et al. in prep.), incorporating species that exceed the range of morphological features known by Tang & O’Brien (2012): 1) Subgenus Parallocorynus consisting of P. bicolor , P. gregoryi , P. jonesi , P. norstogi , P. perezfarrerai and P. salasae , 2) Subgenus Dysicorynus consisting of P. andrewsi and P. sonorensis , 3) Subgenus Neocorynus consisting of P. iglesiasi and P. inexpectatus , and 4) Subgenus Eocorynus consisting of P. chemnicki and P. schiblii . These subgenera are distinguished by a combination of characters including: larval feeding site and pupation site, adult color, rostral length/pronotal length, pronotal width/length, shape of sternite VIII of females, spination in adult male profemora and shape of the penis. The first two subgenera were previously incorporated in the “bicolor ” group of Tang & O’Brien (2012) and can be separated from the latter two subgenera by the lack of spination in the profemora of the males. The first two subgenera may be distinguished from one another by color, which is orange-brown and black in the subgenus Parallocorynus versus uniform brown in Dysicorynus , by the shape of the apex of the penis, which is twice as long in Dysicorynus , and by the length of the spermathecal tube, which is more than twice as long in Dysicorynus . As in all other genera of Allocorynina , the pupae of the first two subgenera complete their development within the male cones of their host cycad species. Furthermore, their larvae confine their development within sporophylls of male cones. In the two subgenera, Neocorynus and Eocorynus , the larvae are relatively mobile and feed within the male cone axis of their host cycad species and the pupae do not complete their development in, nor do the adults emerge from, male cones, indicating that these two subgenera have developed fundamental differences in their life cycle compared to all other Allocorynina . Members of Neocorynus and Eocorynus may also be distinguished from the first two subgenera by the presence of granules on the ventral surface of the profemora of the males. Members of Neocorynus and Eocorynus may be distinguished from each other by rostral length/pronotal length of adult females, which is 1.77–1.95 (n = 12) in Eocorynus and 1.55–1.75 (n = 15) in Neocorynus , and also by the presence of a large spine on the ventrodistal apex of the male profemora in Eocorynus that is absent in Neocorynus . Members of the subgenus Parallocorynus may co-occur with a species of either Neocorynus or Eocorynus within the dehiscing male cones of narrow-leaflet Dioon species. Neocorynus and Eocorynus , however, have not been found to co-occur within cones or within the same host Dioon species and appear to have radiated separately within different geographic regions. Tang et al. (1987) measured significant starch levels in tissues of male Dioon cones (2% and 17% dry weight in axis and sporophylls, respectively), which drop sharply as the cones undergo heat production and pollen shed. This starch and other nutrients within male cones probably provide a critical nutrition for developing beetles. The radiation of these three subgenera appears to be the result of niche partitioning of food resources in male Dioon cones, with each group specializing in a different part of the cone. Thousands of Parallocorynus weevils may be found on a single male Dioon cone and there must be intense competition for this abundant (but ephemeral) food resource, which has driven evolution and diversification in these weevils. Molecular analysis of the 16S rRNA gene ( Tang et al. in prep.) supports the distinction of these four subgenera as natural groupings and also indicates that the genus Parallocorynus is one of the more derived lineages of extant Allocorynina and is sister to Rhopalotria .

Biology— Large amounts of cycad pollen were found in the hindgut of adults of all species of Parallocorynus examined in this study, except for P. sonorensis , where only reared specimens with empty guts were available. This suggests that Dioon pollen is the main food item in adult Parallocorynus . In all other adult Allocorynina examined herein the hindgut contained mainly unidentified tissues and only occasional cycad pollen grains. In a detailed (1989) study Norstog & Fawcett concluded that Rhopalotria furfuracea does not feed on pollen, but microsporophyll tissue in its host Zamia . Taken together these observations indicate a different adult feeding strategy in Parallocorynus compared with other Allocorynina genera.

Host and Geographic Distribution— This lineage is restricted to Mexico and all members of this genus inhabit male cones of narrow-leaflet Dioon species, including D. angustifolium , D. argenteum , D. califanoi , D. caputoi , D. edule , D. holmgrenii , D. merolae , D. purpusii , D. sonorense , D. stevensonii and D. tomasellii .

Subgenus Parallocorynus Voss, 1943

Type species: Allocorynus (Parallocorynus) bicolor Voss, 1943

DIAGNOSIS. The subgenus Parallocorynus can be distinguished from all other Allocorynina by the following combination of characters: ventral surface of male profemora without granules, spines or pegs; apex of the penis as long as wide; forehead and prothorax uniformly brown or orange-brown.

DESCRIPTION. Body small to large (BL = 2.5–6.2 mm, mean = 4.2 mm, n = 325); robust, elongate broad-oval; dorsal surface bicolored orange to black, with portion of elytra often partially black and other parts of body and legs with same two colors.

Male. Rostrum: 0.96–1.40X as long as pronotum (n = 158). Anntenae: scape length 1.19–2.61 X eye length (n = 30; mean for each species = 1.46–2.23); width of antennal club pits>, ~ or <diameter of socket for rhopalomere (Figs. 113–118). Prothorax: pronotal width/pronotal length (PW/PL) = 1.12–1.37 (n = 158); distance from anterior margin of procoxae to anterior margin of prosternum on average 2.6–3.9 X distance from posterior margin of procoxae to posterior edge of prosternum. Legs: profemora with absence of any spines, pegs, or granulations on ventral surface; not asymmetrically swollen.

Female. Same as male except: Rostrum: 1.27–1.66 X longer than pronotum (n = 143), on average 14–35% greater in females. Prothorax: PW/PL = 1.23–1.51 (n = 144), on average 3–9% greater in females than in males, with slight overlap between sexes in all species.

Genitalia and Associated Structures— Male. Length of penis and apodemes together 1.20–1.64 (1.76 in one specimen atypically straightened) mm (n = 31), reaching greatest length in Allocorynina . Penis: in dorsal view sides subparallel or converging slightly apicad for most of length, length to width ratio 2.9–3.6, slightly expanding laterally before apex at approximately 2/3 from base, or not (Figs. 149–160); apex narrowing evenly apicad to rounded point; length of apex from orifice to apex ~ width of apex at orifice (Figs. 185–190). Internal sac: distal section mostly covered by scales laterally and ventrally with dorsal pleats, sinuate endophallic strut present along ventral midline (Figs. 150, 152, 154, 156, 158, 160, 239). Tegmen: apical plate in dorsal view slightly narrowing distad to truncate or slightly rounded apex, apex fringed with 20–30+ setae; length of longest setae> half width of apical plate in dorsal view (Figs. 205–206, 225–230). Female. Sternite VIII: (Figs. 252–257) 0.96–1.47 mm long (n = 23), arms ~ half as long as apodeme, diverging from apodeme at constant or slightly increasing angle between arms for 2/3–4/5 of length, then forming sharp angulate bend, then usually converging (apices not touching) but sometimes becoming subparallel. Spermathecal tube: with uncoiled length <half length of sternite VIII (Fig. 265).

Remarks— As here delimited this nominate subgenus corresponds to the “bicolor ” species group of Tang & O’Brien (2012), but excludes a portion of the western species, which have been separated out in the subgenus Dysicorynus .

Host and Geographic Distribution— This subgenus appears restricted to eastern and southern Mexico and all members of this subgenus inhabit male cones of narrow-leaflet Dioon species, as larvae, pupae and adults. Host species include D. angustifolium , D. argenteum , D. califanoi , D. caputoi , D. edule , D. holmgrenii , D. merolae and D. purpusii . Adults have been reared in the laboratory from male cones of D. angustifolium , D. caputoi , D. holmgrenii and D. merolae .