Pariaconus caulicalix 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 : 56

Pariaconus caulicalix Percy sp. n. Figures 25, 49 A–J

Adult colour.

General body colour is either brown to dark brown, or light red to red-brown. Fore wing membrane clear or slightly fuscous.

Adult structure.

Fore wing apex bluntly acute; surface spinules distributed in all cells except few or none in r1; short setae on margins and veins (Fig. 25A). Antennae short (av. length 0.71; ratio AL:HW av. 1.41); genal processes short (ratio VL:GP av. 3.17); short to minute setae on vertex and thorax; distal proboscis segment short (av. length 0.11); hind tibia length subequal to head width (ratio HW:HT av. 1.06) (Fig. 25 B–G). Male terminalia (Fig. 25 H–K): paramere shorter than proctiger (ratio MP:PL av. 1.14), broader at the base and tapering to an elongate neck below a somewhat flat-topped apex with anteriorly directed hook; distal aedeagus segment length subequal to paramere (ratio PL:AEL av. 0.99) with base rounded or slightly angular and slightly inflated, and a moderately large acutely hooked apex (ratio AEL:AELH av. 2.73). Female terminalia (Fig. 25 L–O): proctiger short, dorsal surface more or less straight, apex acute, anal ring long (ratio FP:RL av. 2.98); subgenital plate with very slight medial bulge ventrally, apex acute to bluntly acute; ovipositor apex with reduced serrations (2 above, 0-2 below), valvulae dorsalis not strongly convex dorsally.

Egg.

Unpigmented to light brown, elongate and sinusoidal, no microsculpturing, short pedicel 1/4 length from base, long tail with slightly inflated tip (Fig. 25 P–Q).

Immature.

Colour and structure: Black or brown dorsally, cream to pale orange ventrally. 5th instar: Broadly ovoid in outline, wing buds only slightly protruding with distinct humeral lobes (Fig. 49 A–B). Dorsal surface with ridges (Fig. 49D). Tarsi with moderately small claws (not extending beyond arolia) (Fig. 49B). Circumanal ring moderately wide (CPW:RW 5.89), shallowly v-shaped, with a single row of elongate cells (Fig. 49A). Chaetotaxy: 5th instar: Continuous marginal ring of blunt sectasetae (Fig. 49C). Dorsal surface with intermittent minute simple setae. 1st instar (Fig. 49F): Margin with broad blunt sectasetae (8 pairs anterior margin of head, 1 pair postocular, 1 pair on each wing bud, 12 pairs on abdomen), and with distinct arrangement of large to medium large, acutely pointed sectasetae dorsally (4 pairs head, 4 pairs thorax, 2-5 pairs abdomen), which are lost by the 3rd-4th instars; by the 2nd instar there is a continuous marginal ring of sectasetae (Fig. 49E).

Host plant notes.

Found predominantly on glabrous and semi-pubescent morphotypes.

Island.

Kauai.

Distribution notes.

The two recognized forms ( brunneis and rubrus ) of Pariaconus caulicalix are found sympatrically (although form brunneis is more widespread), which, given the molecular differentiation, suggests that, in addition to colour and general size differences that are noticeable in the field, there may be some reproductive isolation.

Biology.

This species forms thin-walled cup galls on stems, often clustered together, with one immature per gall chamber (Fig. 49 G–J). The gall tissue of the cup is green or yellow-green. Immatures are seated in the base of the cup gall and the ridged sclerotized dorsal surface forms a plug under which is the soft unsclerotized body (Fig. 49 G–H).

Etymology.

The name refers to the gall type which is a cup (calix) -shaped cambial outgrowth on plant stems (caulae) (adjective in the nominative singular).

Comments.

Two forms are recognized (Fig. 25): form brunneis (more common, larger and generally brown, with a longer paramere), and form rubrus (smaller, generally orange-red, and shorter paramere); there are few other morphological characters to distinguish these forms, however there is notable genetic divergence (Fig. 3). This is one of the more common species on Kauai and is closely related to Pariaconus crassiorcalix , which makes a thick-walled cup gall on stems of more pubescent morphotypes such as bog ohia in Alakai Swamp. Morphologically, both these species are close to Pariaconus lehua (Crawford, 1925).

Type material.

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