Pariaconus oahuensis 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 : 66-70

Pariaconus oahuensis Percy sp. n. Figures 31, 32, 33, 50 A–D, F, I–L

Trioza iolani Kirkaldy, 1902: 114, in part (Oahu specimens, nec Kauai specimens)

Trioza iolani sensu Crawford, 1918: 441, 1925: 27

Trioza iolani sensu Zimmerman, 1948: 21

Adult colour.

General body colour yellow-green to yellow-brown. Females often appear to have a dark abdomen due to darkly pigmented egg load. Fore wing membrane clear.

Adult structure.

Fore wing apex rounded; spinules distributed in all cells, but few in r1; medium to long setae on margins and veins (Fig. 31 A–D). Antennae long (av. length 1.31; ratio AL:HW av. 2.02); genal processes medium-long (ratio VL:GP av. 1.62), and apically bluntly acute (forms oahuensis and tenuis ) or rounded (form latus ); medium-long setae on vertex and thorax; distal proboscis segment short (length 0.11); hind tibia longer than or subequal to head width (ratio HW:HT av. 0.90) (Fig. 31 E–P). Male terminalia (Fig. 32 A–C): paramere length subequal to or longer than proctiger (ratio MP:PL av. 0.82), broad at the base and more or less parallel-sided (f. oahuensis ), tapering (f. tenuis ), or inflated medially (f. latus ) before constricting to a short neck below an apex with anteriorly directed hook; distal aedeagus segment shorter than paramere (ratio PL:AEL av. 1.18) with base rounded and slightly inflated, and a shallow hooked apex (ratio AEL:AELH av. 2.57). Female terminalia (Fig. 33 A–F): proctiger long, dorsal surface more or less straight or slightly convex, apex acute to bluntly acute, anal ring extremely short (ratio FP:RL av. 7.55); subgenital plate with slight medial bulge ventrally, acute to bluntly acute apically; ovipositor apex lacking serrations, valvulae dorsalis moderately or slightly convex dorsally.

Egg.

Short, broad, pigmented brown to dark brown (except tip of pedicel and tail) with surface microsculpturing, either with long pedicel and tail, the pedicel with an inflated tip (forms oahuensis and tenuis ), in form latus eggs are more slender, lighter in colour with finer surface microsculpturing, a much shorter pedicel without inflated tip, and an unsclerotized patch at the base of the egg likely in the position where the egg contacts the plant surface (in populations making cone leaf galls, the tail is extremely short and there appears to be no pedicel) (Fig. 33 G–I).

Immature.

Colour and structure: 5th instar: Cream to orange. Elongate ovoid in outline, wing buds protruding with moderate humeral lobes (Fig. 50A, C). Tarsi with large claws (Fig. 50B). Circumanal ring small (CPW:RW av. 24.40), u-shaped with a single row of sometimes interrupted cells (Fig. 50D). 1st instars have a scaly dorsal surface (Fig. 50F). Chaetotaxy: 2nd-5th instars: Head, thorax and abdomen with scattered long to medium-long simple setae. 1st instar (Fig. 50F): Setal arrangement similar to those in the bicoloratus group; marginal sectasetae narrow, anterior margin of the head with simple setae, a single pair of post ocular sectasetae, a single pair of sectasetae on the apices of each wing bud, and the margin of the abdomen with 8-10 pairs of sectasetae.

Host plant notes.

Primarily on more pubescent morphotypes.

Island.

Oahu.

Distribution notes.

The distribution ranges of the three recognized forms overlap, all three are found in both Waianae and Koolau ranges, but rarely at the same collec tion site suggesting microecological divergence may play a role in explaining this diversity; form oahuensis is the most widespread, form tenuis and form latus are generally less common; however form tenuis appears to be the more common in the southern Waianae and form latus the more common in the southern Koolau, and therefore initial divergence may have taken place allopatrically between the two primary mountain ranges, with subsequent expansion and secondary overlap of ranges.

Biology.

Usually galls stems, buds and petioles resulting in irregular swellings (Fig. 50I), but a localized population in the northern Koolau Mnts makes distinct cone galls on leaves resembling those of Pariaconus pyramidalis (Hawaii) but with a different opening mechanism (4-5 valves opening from the apex of the gall on the lower leaf surface, versus a circular suture and trap-door opening on the upper leaf surface in Pariaconus pyramidalis , compare Fig. 50 J–L with Fig. 52 T–X). See discussion on lability of galling biology. Dense clusters of gall chambers in bud galls can yield>10 immatures per bud.

Etymology.

Named for its distribution on the island of Oahu (noun in the genitive case).

Comments.

One of the commonest species on Oahu. It can be distinguished most easily from other Oahu species by its typically much larger size and predominantly yellow-green or yellow-brown colour. This species encompasses Trioza iolani sensu Crawford (1918, 1925) and Zimmerman (1948), see comments under Pariaconus iolani (Kirkaldy). Three forms are recognized (Figs 31-33): form oahuensis (based on the type, with variably broad paramere, and shorter, more apically blunt female terminalia), form tenuis (narrower paramere, long slender female terminalia constricted apically), and form latus (with the broad est paramere that is somewhat medially expanded, long female terminalia not apically constricted, and eggs with unsclerotized base), this latter form apparently also includes the populations that produce cone galls on leaves in the northern Koolau Mnts.

Type material.

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