Pariaconus nigricapitus (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 : 23-25

Pariaconus nigricapitus (Crawford, 1918) Figures 5, 45 A–E

Kuwayama nigricapita Crawford, 1918: 446.

Kuwayama nigrocapita wrong spelling of Kuwayama nigricapita Crawford in Crawford (1925): 424.

Pariaconus nigricapitus (Crawford), Enderlein (1926): 401; Burckhardt and Ouvrard (2012): 22.

Pariaconus nigricapatus wrong spelling of Pariaconus nigricapitus (Crawford) in Enderlein (1926): 401.

Adult colour.

Typically bicoloured, generally pale cream-yellow to green on thorax and abdomen, head darker, with a dark dorsal stripe from the head extending part or all the length of the body. Fore wing membrane clear or slightly fuscous.

Adult structure.

Fore wing apex rounded; surface spinules dispersed, usually in all cells but may be reduced or absent in r1 and c+sc; setae on margins and veins short to minute (Fig. 5A). Antennae short (av. length 0.68; ratio AL:HW av. 1.38); genal processes extremely short (ratio VL:GP av. 4.81); short to minute setae on vertex and thorax; distal proboscis segment short (av. length 0.07); hind tibia subequal to head width (ratio HW:HT av. 1.03) (Fig. 5B, D). Male terminalia (Fig. 5C, H): paramere shorter than proctiger (ratio MP:PL 1.20), broad at base, tapering to narrow neck below apex with short interiorly directed hook; distal aedeagus segment length subequal to paramere (ratio PL:AEL 1.00), base slightly angular and moderately inflated, apex developed into a dorsally flattened, bluntly rounded hook (ratio AEL:AELH 2.00). Female terminalia (Fig. 5E, I-K): proctiger dorsal surface more or less straight, apex blunt, longer than subgenital plate (ratio FP:FSP av. 1.41), anal ring long (ratio FP:RL av. 2.20); subgenital plate with no or slight medial bulge ventrally, apex truncate; ovipositor apex with serrations (3 pronounced lower, and 2 pronounced upper), valvulae dorsalis strongly convex dorsally.

Egg.

Unpigmented or light brown, broad and moderately long with uninterrupted striations over entire surface, short pedicel 1/4 length from base, tail moderately long (Fig. 5 F–G).

Immature

(note: immature association for Pariaconus nigricapitus is based on immatures with the same collection data as the holotype, but given the co-occurrence of taxa, this remains to be confirmed with DNA analysis). Colour and structure 5th instar: Mid to dark brown. Broadly ovoid in outline with more or less uninterrupted circumference, and the entire dorsal surface raised into a sclerotized dome resulting in a smooth lacquer-like casing (Fig. 45 A–C, E). Fore wing buds with distinct humeral lobes. Tarsi with small reduced claws (Fig. 45D). Circumanal ring broad and shallowly v-shaped, with a single row of elongate cells (Fig. 45A). Four protruding mounds of tissue each terminating in a cluster of distinctly enlarged cells are situated ventro-anterior to the meso and meta coxae (Fig. 45A; also present in open gallers, e.g. Fig. 48N), similar structures were found in the same position on Pariaconus minutus instars within pit galls, and these likely aid either in attachment to the plant surface, or in positional shifting within a gall but are usually no longer visible after preparation for slide mounting and so are illustrated here for the first time using the imprint left in the casing of Pariaconus nigricapitus . Chaetotaxy: The entire outer margin is ringed with fused setae resembling reduced sectasetae (Fig. 45A). Dorsum without setae, or with sparse minute simple setae.

Host plant notes.

Unconfirmed, but may prefer more glabrous morphotypes.

Island.

Molokai, Lanai, Hawaii.

Distribution notes.

Although treated broadly as occurring on three islands (based on previous records summarized in Zimmerman 1948), further sampling from Molokai and Lanai is required to confirm this distribution. Only two species from the bicoloratus group were collected on Molokai during this study ( Pariaconus hina , Pariaconus lona ).

Biology.

The immatures described here are considered free-living but develop under a domed casing which remains after the adult has enclosed (see note on need to confirm adult-immature association).

Comments.

Belongs to a complex of species within the bicoloratus group (" bicoloratus species complex" Figs 1-2) for which there is scant biological knowledge, but all the taxa may be non-galling. The species complex includes Pariaconus nigricapitus , Pariaconus hina , and Pariaconus wyvernus with notably truncate female genitalia, and three other species ( Pariaconus nigrilineatus , Pariaconus proboscideus , Pariaconus kapo ). All species appear to have a scattered distribution, occur at low abundance and are infrequently collected; immatures are rarely encountered, and the adult morphology is often cryptic (close examination of slide mounted specimens is required). A complete taxonomic concept of Pariaconus nigricapitus remains somewhat uncertain due to the fact that the type material consists of a single entire female, and a partial male specimen with the abdomen missing. Because female morphology is similar among three species in the species complex, the association of the type female specimen with conspecific male counterparts is challenging. Similarly, due to the sympatric co-occurrence of taxa in this species complex, the association of the immature described here, which was collected by O. Swezey in May 1917 with the adult type material of Pariaconus nigricapitus , remains to be confirmed.

Type material.

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