Pariaconus pyramidalis Percy

Percy, Diana M., 2017, Making the most of your host: the Metrosideros-feeding psyllids (Hemiptera, Psylloidea) of the Hawaiian Islands, ZooKeys 649, pp. 1-163 : 84-87

Pariaconus pyramidalis Percy sp. n. Figures 44, 52 D–I, S–Y

Adult colour.

General body colour brown or yellow-brown, or yellow-green, the genal processes are often paler than the head. Females often appear to have a dark abdomen due to darkly pigmented egg load. Fore wing membrane clear, or slightly fuscous.

Adult structure.

Fore wing apex rounded; spinules distributed in all cells; short setae on margins and veins (Fig. 44A). Antennae medium-long (av. length 1.06; ratio AL:HW av. 1.75); genal processes medium-short (ratio VL:GP av. 1.94), bluntly acute to acute; medium-short to short setae on vertex and thorax; distal proboscis segment short (av. length 0.09); hind tibia length subequal to head width (ratio HW:HT av. 0.97) (Fig. 44 B–C, F, H). Male terminalia (Fig. 44 D–E): paramere longer than proctiger (ratio MP:PL av. 0.84), broad and more or less parallel-sided basally before tapering to apex with anteriorly directed hook; distal aedeagus segment shorter than paramere (ratio PL:AEL av. 1.17) with base rounded, slightly inflated, and a shallow hooked apex (ratio AEL:AELH av. 2.21). Female terminalia (Fig. 44G): proctiger long, dorsal surface slightly to moderately convex, apex acute, anal ring medium-short (ratio FP:RL av. 6.23); subgenital plate with slight to moderate medial bulge ventrally, acute apically; ovipositor apex lacking serrations, valvulae dorsalis slightly convex dorsally.

Egg.

Short, broad, pigmented brown to dark brown (except tip of pedicel and tail) with surface microsculpturing, long pedicel with inflated tip, tail long (Fig. 44I).

Immature.

Colour and structure: 5th instar: Cream to orange. Elongate ovoid in outline, wing buds protruding with moderate humeral lobes (similar to Pariaconus hawaiiensis in Fig. 52A). Tarsi with large claws. Circumanal ring small (CPW:RW av. 16.96), u-shaped with patches of single or multiple rows of interrupted cells (Fig. 52 D–E), sometimes reduced or absent. Chaetotaxy: 5th instar: Head, thorax and abdomen with scattered long to medium-long simple setae (Fig. 52F, I). 1st instar (Fig. 52H): Setal arrangement similar to Pariaconus oahuensis , with simple setae on anterior margin of head and otherwise narrow, blunt sectasetae (a single pair post ocular, a single pair on the apices of each wing bud, and 7-8 pairs on the abdomen); by the 2nd instar all setae are simple (as is typical of ohialoha group) (Fig. 52G).

Host plant notes.

Known from both glabrous and pubescent morphotypes.

Island.

Hawaii.

Distribution notes.

This species is widely distributed on Hawaii. The molecular data suggests an initial diversification in the south western part of the island and subsequent spread north, west, and east.

Biology.

Although predominantly makes cone galls on leaves (Fig. 52 S–V), two immatures were dissected from stem galls and one from a flower bud gall that DNA barcoded to this species, suggesting that some lability in galling exists (see Discussion). The cone gall extends from the lower surface of the leaf and the galls typically open on the upper leaf surface by a suture around the margin of the gall resembling a hinged trap door (Fig. 52W, X). The shape of the cone gall can vary depending on the host morphotype, galls on pubescent types tend to be broad and short (Fig. 52 U–V), while those on glabrous types tend to be more narrow and elongate (Fig. 52 S–T), in both cases gall tissue often becomes reddish in colour. Galls can be scattered across the leaf surface (Fig. 52 X–Y) or clustered (Fig. 52V), and in some cases are found clustered linearly along the leaf midrib (Fig. 52S).

Etymology.

Named for the shape of the pyramid-like cone gall produced on leaves (adjective in the nominative singular).

Comments.

This species is sister to Pariaconus hawaiiensis ; the switch from stem/bud galling to cone leaf galling happened in situ on Hawaii, and reflects a parallel process found on Oahu in a localized population of Pariaconus oahuensis , which although normally a stem/bud galler, produces a cone leaf gall in a localized population in the Koolau Mnts. Some lability apparently still exists on Hawaii because a localized population of Pariaconus pyramidalis was found with two individuals dissected from stem galls.

Type material.

Holotype male (slide mounted, BMNH). See Table 2 for details of type and other material examined for this study.