Paraplea bifurcata, Cook, 2021

Cook, Jerry L., 2021, Review of the Paraplea Esaki & China (Hemiptera: Heteroptera: Nepomorpha Pleidae) of Australia, with description of a new species, Zootaxa 4985 (1), pp. 81-90 : 83-85

Paraplea bifurcata n. sp.

( Figs. 1-8 )

Type Material: HOLOTYPE Female. Australia, Northern Territory, Howard River at Gunn Point Road , 12 IX 2002, G. Challet, deposited in Australian National Insect Collection ( ANIC).

PARATYPES Same collection data as holotype , 1 male deposited in ANIC , 1 male and one female deposited in UMC , 2 males deposited in SHSU.

Description: Measurements of type series (mm): total length 1.62–1.81, body depth (greatest height of hemelytra) 0.52–0.70, greatest body width 0.85–0.92; BSI 50–57.

Color: Body generally tan with brown markings and occasional favose (honeycomb) pattern that is almost white (Fig. 1,2). Brown markings usually restricted to surrounding some punctures on the elytra ( Fig. 1, 2 ), faint brown makings between eyes ( Fig. 3 ) and on pronotum ( Fig. 1 ), legs tan, mouthparts brown, eyes silver to red ( Figs. 1–3 ).

Head: Triangular in frontal view ( Fig. 3 ), vertex convex in frontal view, tan with slightly darker markings associated with faint punctures, darker steak usually present between eyes ( Fig. 3 ), setae present but difficult to see, width 0.79–0.85; distance between eyes 0.36–0.44, OI 47–52 (distance between eyes subequal to combined width of eyes); antenna three-segmented, concealed below eye by cuticular ridge; mouthparts short ( Fig. 3 ), extending just past base of prothoracic coxa, darker than rest of head.

Thorax: Pronotum usually with slight lateral bulge posteriorly, distinctly wider than long ( Fig. 1 ), length 0.48– 0.62, width 0.85–0.94, PI 53–73, posterior center slightly indented medially ( Fig. 1 ), honeycomb pattern barely visible ( Fig. 1 ); pits small, diameter about 0.02, closely packed ( Fig. 1 ). Scutellum slightly wider than long, width 0.38–0.43, length 0.35–0.41, SI 105–123, color uniform, pits obscured, honeycomb absent.

Wings: Hemelytral pits similar in size to thoracic pits but 0.04–0.05 apart, most dark brown except for pits on anterior clavus and portion of clavus near scutellum ( Fig. 1 ), each pit surrounded by honeycomb; claval suture complete ( Fig. 1, 2 ); long hairs common, each associated with hemelytral pit; membranous flight wings present, completely covered by elytra.

Legs: Prothoracic and mesothoracic femur with small spines along ventral side; setae present on most leg segments, most common on coxa, trochanter, tibia and tarsus; metathoracic tibia and tarsus longer than on other legs; leg dimensions as in Fig. 4 .

Ventral keel: first four abdominal segments with bifurcated keel in ventral view ( Fig. 5 ); thoracic segments irregularly shaped as in Fig. 6 , only mesothoracic keel with teeth, prothoracic and metathoracic keel rounded.

Male characters: Male genital plate generally triangular, longer than wide, width 0.27, length 0.36, setae throughout except for small area near apex, rugose sculpture throughout but most apparent near apex ( Fig. 7 ).

Female characters: Genital plate with lateral sides curved. ( Fig. 8 ), about as wide as long, width 0.12, length 0.13, tufts of long coarse setae at sides approximately half the distance to apex, sparse setae on other parts of plate, rugulose sculpture throughout ( Fig. 8 ); ovipositor most commonly as in Fig. 9 . First gonapophyses of ovipositor small, with numerous teeth, width 0.07, length 0.21, with eight distinct teeth along posterior border (apical row), three ventral teeth, two primary teeth, two secondary teeth, three tertiary teeth, accessory tooth between primary and secondary row above ventral tooth 1, at least two additional accessory teeth posterior of T 3.

Discussion and diagnosis: The single character that separates Paraplea bifurcata n. sp. from all other species of pleids is its bifurcated abdominal keel. This is an easily observed apomorphy for this species. In many other characters, P. bifurcata n. sp. most closely resembles P. brunni . Paraplea bifurcata n. sp. has a body shape similar to P. brunni , although there are distinct differences in sculpturing. Paraplea bifurcata n. sp. has a pronotum that is evenly sculptured with punctures throughout and exhibits little or no honeycombing. Paraplea brunni has a pronotum that lacks punctures in the center but has punctures laterally. The pronotal punctures are much smaller and more tightly packed in P. bifurcata n. sp. compared to those in P. brunni . The scutellum has similar differences between these species. Paraplea bifurcata n. sp. has a somewhat rugose scutellum, with punctures not discernable. Paraplea brunni has a smooth scutellum with a small number of unevenly spaced punctures. Both species have the punctures on the hemelytra similarly darkened but these punctures are associated with relatively longer hairs in P. bifurcata n. sp. The size of P. bifurcata n. sp. and P. brunni does not appear to overlap, with P. brunni being larger. Paraplea brunni is reported to have a total length between 1.9 to 2.1 mm, varying little throughout its geographical range (in the specimens examined for this study, as reported in the materials and methods, all were about 2mm). Paraplea bifurcata n. sp. is described as not being more than 1.81 mm, averaging about 1.7 mm.

The genital plates of P. bifurcata n. sp. are interesting in their differences between the male and female, and they are diagnostic for this species. The male genital plate is not unusual for a species of Paraplea in its relative size and dimensions, although it has more setae than are found on most species. The female genital plate of P. bifurcata n. sp. is much smaller than the male genital plate, although the total body length of this species is similar (females appear to be slightly larger than the male although it is difficult know if this generalization holds true since only two females and six males were used for this study). This large difference in size of genital plates within a species is unusual. Setae on the female genital plate are longer than in the male, especially the lateral tufts. While lateral tufts are usual for female genital plates, the setae of B. bifurcata n. sp. are unusually long and thick. The first gonapophysis of the ovipositor shares similarities with P. brunni but P. bifurcata n. sp. has more teeth, even though the ovipositor of P. bifurcata n. sp. is smaller. There are also differences in size and the placement of some teeth when comparing these species.

Distribution: Known only from type locality.

Ecology: Nothing is known of the ecology of this species.

Etymology: The specific epithet comes from an apomorphy of having a bifurcated keel in the first four abdominal segments.

Diagnosis: The bifurcated keel on the first four abdominal segments is an easily seen characteristic that will distinguish this species from all other members of Pleidae .

Figures

FIGURE 4. Legs of Paraplea bifurcata n. sp., prothoracic leg at top, mesothoracic leg in center, and metathoracic leg at bottom. Scale bar = 0.1mm.

FIGURE 9. First gonapophysis of the ovipositor of Paraplea bifurcata n. sp. Teeth with numbers (1–8) are apical teeth; ventral teeth are designated with a V and their positional number; those with P, S, and T represent primary, secondary and tertiary teeth respectively. All other teeth are considered accessory teeth. Scale bar = 0.1.

FIGURES 1–3. Paraplea bifurcata n. sp. (1) Dorsal, (2) lateral, and (3) anterior views.

FIGURES 5 & 6. Paraplea bifurcata n. sp. (5) ventral view of abdomen with bifurcated keel on first four abdominal segments, (6) profile of keel with prothoracic segment at top and fourth abdominal segment at bottom.

FIGURES 7 & 8. Paraplea bifurcata n. sp. genital plates, (7) male genital plate and (8) female genital plate. Scale bars = 0.1mm.