Neogreenia MacGillivray, 1921

Zheng, Xinyi, Watson, Gillian W., Zhang, Jiangtao, Tan, Zhixiang & Wu, San’An, 2024, A review of the genus Neogreenia MacGillivray (Hemiptera: Coccomorpha: Qinococcidae) with descriptions of two new species, Zootaxa 5418 (5), pp. 401-441 : 404-407

Genus Neogreenia MacGillivray, 1921

Paragreenia MacGillivray 1921: 78 , junior homonym (used in Arachnida, 1907).

Neogreenia MacGillivray 1921: 474 (replacement name for Paragreenia ).

Kuwaniella Tang, 1984: 123 , nomen nudum.

Type species: Monophlebus zeylanicus Green, 1896 .

Genus description

Adult female. In life, body elongate, 3.1–8.2 mm long, yellow to orange, bare or scantily covered in mealy white wax; derm membranous. In microscope slide mount, antennae each 10 segmented, located on apex of head, apical segment with a truncated apex. Mouthparts present. Legs developed, each with trochanter bearing 3 or 4 sensory pores on each surface; tibia with tuft of long digitules at distal end; tarsus 1 segmented; claw with 2 or 3 small denticles and a pair of pointed digitules, shorter than claw. Thoracic spiracles each with sclerotized bar and sieve-like disc-pores within atrium. Abdominal spiracles numbering 8 pairs: anterior 6 pairs each with pores within atrium, posteriormost 2 pairs tube-like. Anal opening simple. Vulva situated on venter of abdominal segment VIII, the opening longitudinal and slit-like, surrounded by wrinkles and 3 apodemes arranged in a triangle. Compound multilocular disc-pores, bilocular compound multilocular disc-pores and simple pores present.

Adult male. In life, body elongate, 1.5–2.3 mm long, wing-span about 4.0 mm; with a dorsal tuft of long waxy filaments on posterior part of body; membranous parts of body yellowish to reddish, sclerotized parts brown, compound eyes black. In microscope slide mount, antennae each 10 segmented and slender; flagellar segments each with many long, hair-like setae. Venter of head with a subpentagonal sclerotization; midcranial ridge lacking; postoccipital suture developed and interrupted. Pronotal ridge sclerotized and uninterrupted; post-tergite with an inverted “π”-like sclerite. Scutellum triangular with a central conical projection on posterior margin. Fore wings each without microtrichia and alar setae, but with sclerotized costal thickening, and pterostigma near wing apex; a line of circular sensoria present on radius; alar lobe fold sclerotized along proximal posterior margin; cubitus anterior sclerotized; cubitus posterior, radial sector and anal fold membranous and clear; media clear and branching at middle. Hind wings each with apex bilobate and several curved hamuli at tip. Legs each with many long and hair-like setae; trochanter with 3 sensory pores on each surface; tarsus 2 segmented; claw with 2 denticles. Caudal extensions absent from abdomen; abdominal segments VI and VII each with a group of large dorsal tubular ducts. Penial sheath sclerotized, aedeagus emerging from a ventral slit in penial sheath; eversible endophallus absent. Loculate pores and simple pores present.

First-instar nymph. In life, body elongate, 0.4–0.7 mm long, body yellow, eyes black; derm membranous. In microscope slide mount, antennae each 7 segmented, with segments VI and VII expanded. Labium 2 segmented; stylets very long. A pair of sclerotized bars present, each originating from outer basal corner of front coxa and extending almost to antennal base. Legs each with trochanter with 3 sensory pores on each surface; claw with a plantar denticle near extremity, and a pair of capitate claw digitules longer than claw. Thoracic spiracles each with sclerotized bar and 1 sieve-like disc-pore in atrium. One pair of abdominal spiracles present, without pores in atrium. Anal opening simple. Abdominal segments VII and VIII each with 1 circular cicatrix. Bilocular or trilocular pores, and simple and compound multilocular disc-pores present. A pair of long caudal setae present.

Second-instar nymph (cyst). In life, body oval, 0.9–1.7 mm long, yellowish; derm membranous. In microscope slide mount, antennae each reduced to small oval plate with several setae. Labium 2 segmented, stylets present. Thoracic spiracles each with a sclerotized bar and several sieve-like disc-pores in atrium. Abdominal spiracles numbering 8 pairs: anterior 5 pairs each sclerotized and with sieve-like disc-pores within each atrium; posteriormost 3 pairs tube-like, without pores. Anal opening simple. Dorsum of abdomen with large simple pores situated submarginally on parts of some segments; compound multilocular disc-pores present marginally but often absent from posterior segments. Hair-like setae present. Eyes and cicatrices absent.

Third-instar female nymph (cyst). In life, similar to the second-instar nymph, but larger, 1.1–3.8 mm long. In microscope slide mount, abdominal spiracles numbering 8 pairs, with anterior 6 pairs sclerotized and with sieve-like disc-pores in atria; posteriormost 2 pairs tube-like, without pores within atria. Large simple pore clusters present submarginally on dorsum of each segment; compound multilocular disc-pores significantly more numerous than in second-instar nymph.

Third-instar male nymph (pre-pupa). In life, body very elongate, 2.9–4.0 mm long, orange; legs and antennae yellowish, eyes black; wing buds absent; derm membranous. In microscope slide mount, antennae each 9 segmented, situated on apex of head. Mouthparts absent. Legs developed, each with trochanter with 3 sensory pores on each surface; tibia with tuft of long hair-like digitules on distal end; claw with 2 denticles. Thoracic spiracles each with a sclerotized bar and sieve-like disc-pores in atrium. Abdominal spiracles numbering 8 pairs: spiracles on abdominal segments VI and VII or posteriormost 3 pairs with sieve-like disc-pores in atria, others tube-like, without pores. Anal opening simple. Large simple pores present dorsally on submargin. Compound multilocular disc-pores each with 4 or 5 subcentral loculi, present on both surfaces of every segment.

Male pupa. In life, body elongate, 1.9–2.3 mm long, with wing buds present; body yellow to orange, abdomen darker, wing buds, antennae and legs yellowish and nearly transparent; derm membranous. In microscope slide mount, antennae each 10 segmented, scape and pedicel with a few hair-like setae, flagellum without setae. Eyes slightly convex. Mouthparts absent. Legs present, each with trochanter with 3 sensory pores on each surface, and claw absent. Spiracles each without pores in atrium; thoracic spiracles each with sclerotized bar.Abdominal spiracles numbering 8 pairs, each sclerotized and tube-like. With a pair of large wing buds on mesothorax, and a pair of small, rounded wing buds on metathorax. Rudiment of penial sheath present on the end of abdomen. A few compound multilocular disc-pores with 3 or 4 subcentral loculi present.

Remarks. After examination of the available specimens, we found that tube-like abdominal spiracles were present in adult females and cysts in all the species examined, which was also noted by Gavrilov-Zimin (2018) and Zheng & Wu (2023b), but had been ignored in earlier works ( Green 1922; Yang & Hu 1994; Tang & Hao 1995; Wu & Cheng 2006; and Wu & Nan 2012). In the past, only one developmental cyst stage was reported ( Wu & Cheng 2006; and Wu & Nan 2012); however, two developmental cyst stages before the adult female were discovered by Zheng & Wu (2023b). In the present work, it was found that the second-instar nymph differs from the third-instar female nymph by having the anterior 5 abdominal spiracles with sieve-like disc-pores in atrium, whereas in the third-instar female nymph, the anterior 6 abdominal spiracles each have sieve-like disc-pores in the atrium.

The adult females of genus Neogreenia can be easily distinguished from the other 3 genera in family Qinococcidae by having a combination of the following features: antennae developed and 10 segmented; legs developed; abdominal spiracles numbering 8 pairs: anterior 6 pairs each with sieve-like disc-pores within atrium, and posteriormost 2 pairs tube-like, without pores (Wu & Zheng 2023a).

Of the seven species of Neogreenia , six are known only from China. The Chinese species share the following characteristics with the type species, N. zeylandica : adult female with 10 segmented antennae; developed legs; mouthparts present; anterior six abdominal spiracles developed and with sieve-like disc-pores within atria; and first-instar nymphs with 7 segmented antennae, each with extremity truncated.

Biology. Neogreenia species live under the bark of woody hosts.They reproduce sexually or parthenogenetically. Neogreenia osmanthus , N. zizyphi and N. zeylanica are known to be bisexual; after emergence, adult females crawl on the bark to find a site for copulation and oviposition ( Zheng & Wu 2023b; Tang & Hao 1995; and Green 1922). Zheng & Wu (2023b) reported that males of N. osmanthus represented a very low percentage (ca. 0.8%) of the population. In contrast, N. sophorica is parthenogenetic; the females do not move but remain under the bark at maturity ( Han et al. 2007). Adult females of all species lay their eggs under the bark.

The general life cycle is illustrated in Fig. 2 . Females of Neogreenia go through four developmental stages (the first-instar crawler, two immature cyst stages and adult); the males go through five stages (the first-instar crawler, an immature cyst stage, third-instar nymph (pre-pupa), pupa, and adult).

Figures

FIGURE 2. Generalized life cycle of Neogreenia.