Trionymus elymus, Gertsson & Hodgson

Hodgson, Chris, 2005, The adult males of Coccoidea (Hemiptera: Sternorrhyncha) known from Greenland, Zootaxa 907, pp. 1-48 : 24-29

TRIONYMUS ELYMUS Gertsson & Hodgson ( Fig. 5 )

Trionymus elymus Gertsson & Hodgson, 2005: 11 .

(Described from 6 specimens, 4 in good condition (although generally abdomens twisted) and most data taken from these; other in fair to poor condition).

Live appearance: not recorded.

Mounted material: small, total body length about 1.02–1.08 mm; antennae short, only slightly more than half total body length, with moderately long, stout fleshy setae (fs); length of fs on antennae slightly greater than width of antennal segments; body with few setae, almost all hair­like (hs), fs setae extremely rare or absent; loculate pores (lp) each with usually 3 to 5 loculi and each 5–7µm wide, on thorax and abdomen only; often with a nearby minute pore. Wings shorter than total body length, about 0.8x total body length and about 0.3x as wide as long. Abdomen with 1 pair of glandular pouches.

Head: roundly triangular, apex of triangle pointing anteriorly; probably with ventral eyes on a distinct postero­ventral bulge; length about 140–160µm; width across genae about 182–190µm. Median crest (mc) absent; postoccipital ridge (por) represented by a thin U­shaped ridge at posterior end of dorsal part of epicranium (dmep); with (on each side) 2–4 fs, 9 or 10 hs dorsal head setae (dhs) but no pores on each side mesad to each scape. Mid­cranial ridge: dorsal ridge (dmcr) rather faint, long and narrow, extending posteriorly well past posterior margin of dorsal simple eyes (dse) and almost reaching postoccipital ridge (por); ventral midcranial ridge (vmcr) absent; lateral arms (lmcr) well developed; group of ventral midcranial ridge setae (vmcrs) fusing with ventral head setae (vhs), see below. Genae (g) not reticulated; with 0–2 fs + 3–6 hs genal setae (gs) on each side. Eyes: two pairs of slightly oval, simple eyes, subequal in size; dorsal eyes (dse) each approximately level with ventral simple eyes (vse); each 23–27µm wide. Ocelli (o) fairly pronounced, situated laterally, each 18–22µm wide, lying just dorsad to where interocular ridge (ior) and postocular ridge (pocr) meet. Ocular sclerite (ocs) lightly sclerotised, with reticulations restricted to immediately around simple eyes. Preocular ridge (procr) well developed, dorsally extending from just anterior to inner margin of dorsal simple eyes antero­laterally to base of each scape (with which it articulates) and then posteriorly to form interocular ridge (ior). Postocular ridge (pocr) strongly developed, extending anterolaterally, ending posterior to inner margin of dse; each fusing with ior just ventral to each ocellus. Dorsal ocular setae (docs) absent. Ventral head setae (vhs): with a total of 7–15 fs, 14 or 15 hs ventral head setae (vhs) (plus ventral mid­cranial ridge setae (vmcrs)) + 3–5 small simple pores anterior and laterad to vse, plus 0 or 1 + 2–4 hs between eyes; some hs rather long (up to nearly 40µm; fs about 25µm long). Preoral ridge (pror) probably weak, with ventral groove and cranial apophysis (ca) arising anteriorly; length of latter combined about 45µm.

Antennae: 10 segmented and filiform; 575–600µm long (ratio of total body length to antennal length 1:0.56). Scape (scp) approximately square, with pedicel arising anterolaterally: 41–45µm long and 41–45µm wide, with 2 hs dorsally and 3 or 4 ventrally and medially. Pedicel (pdc): length 53–57µm, width 33–35µm; with concentric ridges on distal end; with 6–10 fs, 9–11 hs + campaniform pore. Segments III–X each about 18–23µm wide; lengths of segments (µm): III: 73–75; IV: 58–60; V: 58–60; VI: 58–60; VII: 54–57; VIII: 56–60; IX: 58–60; fs about 23–33µm long (longest nearer apex); approximate number of setae per segment: III: 4–10 fs + 1–4 hs; IV: 8–11 fs + 1 or 2 hs; V: 10–12 + 1 or 2 hs; VI: 8–12 fs, 1 or 2 hs + 2–4 caps; VII: 8–12 fs, 0 hs + 4 or 5 caps; VIII: 9–13 fs, 0 or 1 hs, 3–5 caps + 1 bristle (abr) (about 2/3rds along segment); IX: 8–12 fs, 0 or 1 hs, 4 or 5 caps + 1 bristle (abr) (about 2/3rds along segment). Segment X with a slightly narrowed apex: length 63–70µm; with 7 or 8 fs, 0 or 1 hs, 4–6 caps + 3 large and 2 small bristles (abr) near apex (these clearly differentiated from fs); with 1 sensilla basiconica (sb) on apex.

Thorax. Prothorax: pronotal ridges (prnr) well developed, with ridges touching medio­dorsally; long, extending ventrally and nearly touching proepisternum + cervical sclerite (pepcv); pronotal sclerite (prn) represented by an unusually long finger­like process extending postero­laterally, length about 33–36µm; without lateral pronotal setae (lpns). Medial pronotal setae (mpns): with 3 or 4 hs + 0 or 1 lp on each side; post­tergite (pt) distinct, with 4 or 5 hs post­tergital setae (pts). With 2 hs lateral prothoracic setae (lps) anteriorly and 3 hs posteriorly on each side. Sternum (stn1) lightly sclerotised; median ridge absent, transverse ridge well developed; with 2 or 3 hs prosternal setae (stn1s) on each side. Anteprosternal setae (astn1s): 1 hs medially; with 0 or 1 fs, 4 or 5 hs antemesospiracular setae (asp2s) + 0 or 1 minute pores on each side.

Mesothorax: prescutum (prsc) with somewhat parallel sides, 66–78µm long, 109– 112µm wide; sclerotised but not reticulated; prescutal ridge (pscr) well developed laterally, narrowing posteriorly; prescutal suture (pscs) absent; with a total of 3 or 4 hs prescutal setae (prscs). Scutum (sct): without any signs of a less sclerotised area medially; sclerotised but not reticulated; distance between prescutum and scutellum 80–85µm; scutal setae (scts) 1 or 2 hs anteriorly (just posterior to prescutum) + 3 pairs hs posteriorly; with a distinct sclerotised apodeme (praa) on anterior margin near prealare (pra); prealar ridge (prar) quite well developed. Scutellum (scl) 70–80µm wide and 37–42µm long; without a scutellar ridge (sclr) or foramen; scutellar setae (scls): 1 pair hs; postnotal wing process (pnp) strong and extending laterally. Basisternum (stn2) 160–165µm wide and 100–105µm long; without a median ridge (mdr); bounded anteriorly by a strong marginal ridge (mr) and posteriorly with a strong precoxal ridge (pcr 2); with a narrow, short, additional ridge, extending ventrally from pcr2 near articulation with mesocoxa; with a total of about 8 hs anteriorly and medially and 3 hs posteriorly, each about 21µm long; lateropleurite (lpl) narrow; furca (f) well developed, narrow­waisted, arms very divergent and extending about 3/4 way to marginal ridge anteriorly. Mesopostnotum (pn2) well developed; postnotal apophysis (pna) well developed. Area bounded anteriorly by scutellum and laterally and posteriorly by mesopostnotum not sclerotised. Mesepisternum (eps2) not reticulated; subepisternal ridge (ser) long and well developed. Postalare (pa) without reticulations; without postalare setae (pas). Mesothoracic spiracle (sp2): width of peritreme 18–20µm, without associated loculate pores. Postmesospiracular setae (pm2s): with 11 or 12 hs posterior to each spiracle plus 11–13 hs medially. Tegula (teg) present, with 2 or 3 hs tegular setae (tegs) on each side.

Metathorax: with 3 or 4 hs metatergal setae (mts) on each side; metapostnotum (pn3) present as a transverse sclerite. Dorsospiracular setae (dss) absent. Dorsal part of metapleural ridge (plr3) present; with small suspensorial sclerites (ss). Posterior part of metapleural ridge well developed; episternum (eps3) sclerotised; with 1 hs postmetaspiracular setae (eps3s) on each side; precoxal ridge (pcr3) well developed, extending medially about 65–75µm; metasternal apophysis (st3a) indistinct or absent. Metepimeron (epm3) well developed. Antemetaspiracular setae (am3s) absent. Metathoracic spiracle (sp3): width of peritreme 19–20µm, without associated lp. Metasternum (stn3) membranous, with 14 or 15 hs anterior metasternal setae (amss) and 0–2 hs posterior metasternal setae (pmss) on each side.

Wings: hyaline, rather short, about 850–875µm long and 300µm wide (ratio of length to width 1:0.35; ratio of total body length to wing length 1:0.82); alar lobe (al) well developed; each wing with 3 hs alar setae (als), plus 3 circular sensoria (sens) just distal to where medial vein branches from radial vein. Hamulohalteres (h): 71–75µm long, 15– 20µm wide; with a single apical hamulus (ham), 40–55µm long.

Legs: metathoracic legs marginally longest. Coxae (cx): I: 85–95; II: 78; III: 85– 90µm long; setae of coxa III: about 11 hs; long setae on each coxa not differentiated. Trochanter (tr) + femur (fm): I: 186–195; II: 186–190; III: 198–203µm long; trochanter III with 7 or 8 hs; each trochanter with 3 circular sensoria on each side arranged in a triangle medially and with strong sclerotised ridges for articulation with femur; long trochanter seta 50–60µm long; femur III with about 2–4 fs + 13 or 14 hs, some up to 35µm long. Tibia (ti): I: 160–165; II: 160–170; III: 198–205µm; tibia III with a total of about 4 fs + 21–23 setae, several becoming spur­like on distal end of leg; with 2 spurs (tibs) on protarsi, 3 or 4 on mesotarsi and 4 on metatarsi, strongest 20–24µm long. Tarsi (ta) two segmented, proximal segment very short and ring­like, length of both segments combined: I: 78–82; II: 78; III: 82µm long (ratio of length of tibia III to length of tarsus III 1:0.41); tarsus III with 1 or 2 fs + 12–14 setae, many spur­like; tarsal spurs (tabs) not differentiated, but seta in this position about 18–22µm long; tarsal campaniform pore (tcp) present; tarsal digitules (tdt) marginally shorter than claw, with small capitate apices. Claws (c) long and thin, nearly 1.5x width of tarsus, almost straight, without a small denticle (cd); length: III: 28–30µm; claw digitules (cdt) setose.

Abdomen: segments I–VII: tergites (at) unsclerotised; small sternite (as) present on VII. Caudal extension (ce) of segment VII absent. Dorsal abdominal setae (ads) (totals across segment): segments I–VII: 6 or 7 hs. Pleural setae: dorsopleural setae (dps) on each side: I: 2 hs + 1 lp; II–VII: 3 hs + 0 or 1 lp; ventropleural setae (vps) (on each side): II: 0 hs; III–VII: 2 hs. Ventral abdominal setae (avs) (totals): II: 2 hs; III–VII: 4–6 hs. With a pair of fairly distinct ostioles (os) laterally between segments VI and VII.

Segment VIII: tergite (at) and sternite (as) sclerotised, without a pair of antero­lateral sclerotisations ventrally; tergite with 2 pairs hs dorsal abdominal setae (ads); sternite with 4 hs ventral abdominal setae (avs); caudal extension (ce) rounded, with 3 hs pleural setae, longest up to 70µm. Glandular pouches (gp) present, shallow, each with numerous loculate pores spreading out around glandular pouch (gp); with 2 rather long glandular pouch setae (gls), each about 235–300µm long, plus 2 or 3 shorter setae, each 35–110µm long.

Genital segment: penial sheath (ps) short, broadest anteriorly, sides converging to a fairly narrow, blunt apex; covered dorsally by a narrow, elongate membranous area which probably represents part of segment IX; with a vertical anal opening (an) at posterior end. Length of penial sheath 100–110µm, greatest width about 75µm (but no specimens lying dorsoventrally). Ventral lateral processes of penial sheath well developed, each with 3 short setae (each 5–7µm long); ventral surface with 2 or 3 other pairs of short setae, each about 13–16µm long; with 2 or 3 pairs of longer setae (each 16–22µm long) on dorsal surface. Basal rod (bra) short but distinct, probably lying more or less vertically. Aedeagus (aed) more or less parallel­sided, extending to end of penial sheath, about 83–90µm long and about 7µm wide, with a membranous apex; curved, lying within penial sheath.

Material examined. GREENLAND: Evighedsfjord, Kangiussaq, 20.vii.2003, on Elymus mollis, S.T. Nielsen: 5/6adΨΨ + 4adɗɗ; Itevleq, eastern end, 22.vii.2003, on Elymus mollis: 1/2adɗɗ ( ZMUC; BMNH; USNM).

Comment. As males and females of this species were collected at the same site off the same host plant, the identity of the males of this species is highly probable.

Males of T. elymus can be separated from other known alate pseudococcid males from Greenland in having the following combination of characters: (i) fleshy setae on both dorsal and ventral surfaces of head; (ii) small simple pores on ventral surface of head (no pores on dorsal surface); (iii) distinct post­tergites, each with 4 hs setae; (iv) at least 3 or 4 antemesospiracular setae on each side; (v) prescutum with rather parallel lateral margins; (vi) many postmesospiracular setae but no loculate pores; (vii) no loculate pores medially on thorax and abdomen, and (viii) only one pair of glandular pouches. For a comparison with the males of T. bocheri and T. thulensis , see under those species.

Figures

FIGURE 5. Adult male of Trionymus elymus Gertsson & Hodgson. Where A = cranial apophysis; D = convex simple pore on head; G = multilocular disc­pores; H = minute pore; J = apical antennal segment; K = lateral view of genital segment; L = tarsus plus claw.