Pariaconus minutus (Crawford, 1918)

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 : 44-45

Pariaconus minutus (Crawford, 1918) Figures 19, 46 G–P

Kuwayama minuta Crawford, 1918: 447.

Pariaconus minutus (Crawford), Enderlein (1926): 401.

Adult colour.

Variable, typically mid- to dark brown throughout, recently emerged adults can be completely pale cream, head often darker than the rest of the body. A population in the Kilauea Iki caldera (form kilaueaiensis ) is typically yellow-orange or dark orange throughout, or occasionally with blue-green abdomens. Fore wing membrane slightly to noticeably fuscous.

Adult structure.

Fore wing apex rounded; surface spinules fairly densely distributed in all cells; setae on margins and veins minute (Fig. 19 A–B). Antennae short (av. length 0.52; ratio AL:HW av. 1.13); genal processes short (ratio VL:GP av. 3.25); minute setae on vertex and thorax; distal proboscis segment short (av. length 0.09); hind tibia length subequal to head width (ratio HW:HT av. 1.00) (Fig. 19 C–H). Male terminalia (Fig. 19 K–N): length of paramere and proctiger subequal (ratio MP:PL av. 0.98), paramere slender, somewhat sinuous (curving posteriorly then anteriorly at the apex), apex with upwardly directed hook; length of distal aedeagus segment and paramere subequal (ratio PL:AEL av. 1.03), base rounded and slightly inflated, apex blunt, somewhat flattened dorsally, not developed into a hook (ratio AEL:AELH av. 2.50). Female terminalia (Fig. 19 I–J, O–Q, T): proctiger dorsal surface slightly undulating, anal ring long (ratio FP:RL av. 2.66), apex acute; subgenital plate with slight medial bulge ventrally, apex acute; ovipositor apex with two reduced serrations above and below, valvulae dorsalis slightly to moderately convex dorsally (Fig. 19T).

Egg.

Unpigmented to light brown, elongate ovoid, not sinusoidal, smooth, without striations, short pedicel 1/5 length from base, tail short to moderately long (Fig. 19 R–S).

Immature.

Colour and structure: Smaller immatures are orange and cream, or yellow-brown, larger become blue-green or remain orange (e.g. Kilauea Iki population). 5th instar: Broadly ovoid in outline and ventro-dorsally flattened with wing buds protruding and distinct humeral lobes (Fig. 46G). Tarsi with small reduced claws (Fig. 46I). Anal ring moderately wide (ratio CPW:RW av. 4.76) and shallowly v-shaped, with a single row of uninterrupted elongate cells (Fig. 46G). Chaetotaxy: 5th instar: Continuous marginal ring of blunt, weakly bisected sectasetae. Dorsal surface either scattered with small pointed sectasetae (form minutus , Fig. 46G), or small to minute simple setae (form kilaueaiensis ). 1st instar (Fig. 46J): Marginal ring of broad, weakly bisected fan-shaped sectasetae (anterior of head with 11-12 pairs, 1 pair postocular, 1 pair on apices of each wing bud, and 11-12 pairs on abdomen). Apparently only in form kilaueaiensis (Kilauea Iki population) are three pairs of narrow sectasetae present on the dorsal surface of 1st instars (1 pair on each of head, thorax, abdomen). By the 2nd instar there is a continuous marginal ring of sectasetae (Fig. 46H).

Host plant notes.

Usually on thick leaved, pubescent or semi-pubescent morphotypes.

Island.

Hawaii.

Distribution notes.

Widespread on Hawaii. The DNA analysis indicates distinct population clusters, but also more dispersal than for other taxa: two distinct clusters in Kohala, a mixed cluster from Olaa, Kilauea, Kau, and Kona Hema, and another cluster almost entirely from Saddle Road with a single Kau sample.

Biology.

Makes pit galls on upper leaf surface. The leaf tissue often forms into a thickened rim of red or yellow around the immature (Fig. 46 L–P). The Kilauea Iki population makes somewhat shallower pit galls on the upper leaf surface of low growing shrubs (~ 1m) in the bottom of the caldera. Eggs are laid individually or in small clusters long the upper leaf margin (Fig. 46K).

Comments.

Two forms are recognized (Fig. 19): form minutus (based on the type, with mature adults usually brown, is a smaller form with more slender paramere), and form kilaueaiensis (with adults typically orange, is larger with a shorter, broader paramere).

Type material.

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