Melzeria horni Green
Creators: name: Hodgson, Chris
name: Miller, Dug
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Eriococcidae
Melzeria
Melzeria horni

description: Melzeria horni Green   
 Melzeria horni Green 1930: 215–216.   
 First-instar nymph (gender not determined) (Fig. 29)   
 Material examined: BRAZIL: São Paulo, Sanat Amaro, on foliage of unknown plant, no date, Julius Melzer (BMNH, USNM): 2/6 first-instar nymphs in mostly fair to good condition. Probably part of type series.   
 Unmounted material. Not seen.   
 Mounted material. Body oval, about equally rounded at both ends. Length about 220–255 µm, width 100–125 µm.   
 Dorsum. Derm membranous, without obvious dermal spinules. Dorsal setae hairlike, each 2–5 µm long; approximately in 2 medial lines, with pairs on all abdominal segments, 1 pair on pro-, meso- and metathorax, plus 2 pairs on head; also with submarginal setae on meso- and metathorax and on head, plus a possible submedial pair on 1st-abdominal segment. Microtubular ducts with a particularly long outer ductule, each about 16–18 µm long, possibly with a small membranous dermal rim; also with a strongly sclerotised distal end, which appears to have a narrow duct running through it; distributed as follows: with a duct opening located just dorsad to each marginal spinose seta on thorax and abdomen, plus 2 further pairs along margin of head (where marginal spines absent); also with pairs submedially on head, mesothorax and 1st-abdominal segment. Loculate pores and macrotubular ducts absent. Anal lobes absent or rounded, membranous; each with a very long apical flagellate seta about 112–116 µm long. Marginally with 2 pairs of short setae between long apical setae, each about 3 µm long. Anus small, 2 µm wide, without an anal ring or anal ring setae but with 2 minute setae on each side ventrally, each about 1 or 2 µm long. Anus surrounded by a slightly quadrate membranous plate, about 7 µm wide.   
 Margin. Marginal setae cupolate-shaped, l4 µm long, each with a broad base (3 µm wide) and a short sharp point; each in a dermal pocket of about same depth as length of seta; with 1 pair on each abdominal and thoracic segment but none present on head. Eyespots fairly small, each 6–7 µm wide, situated on margin near base of antennae.   
 Venter. Derm membranous. Loculate pores with mainly 5 loculi: with 1 immediately laterad to each peritreme plus another near margin on each side of metathoracic segment. Microtubular and macrotubular ducts absent. With 3 pairs of long setae between antennae (anterior pair longest (about 10 µm long) and possibly submarginal); setae mesad of meso- and metacoxae apparently absent; with a pair of small setae (each 2–3 µm long) medially on abdominal segments II – VI; submarginal setae as follows: 1 minute seta on abdominal segments I– VII, 1 or 2 near each thoracic marginal spine and 1 on either side of simple eye; also with 1 on each side of abdominal segment II – VII in an inner submarginal line.   
Antennae 6 segmented, about 50–59 µm long; segment IV shortest; setal distribution: scape 1; pedicel probably 0; segments III 0 or 1 setose setae; IV & V 1 setose seta + 1 fleshy seta; VI 3 fleshy setae, 2 short setose setae plus 3 long setae; length of longest about 30 µm. Clypeolabral shield about 60–68 µm long, apparently extended somewhat anteriorly; labium probably 2 segmented, about 28 µm wide, 22 µm long, with possibly 3 pairs of short setae distally near apex. Spiracles very small, peritremes possibly 4 µm wide, probably without lateral membranous cavity. Legs well developed; lengths: (metathoracic leg (µm)): coxa 20– 21; trochanter + femur 28–34; tibia 18–20; tarsus 11–13; claw 9; setae: coxae 0?, trochanter 1 longish seta, femur 1, tibia 1 (2?), tarsus 2; long trochanter seta 13 µm long; tarsal campaniform sensillum present; claw with a small denticle; both tarsal digitules on all legs capitate and equal in size; claw digitules alike with small capitate apices.  
 Comment. The first-instar nymphs of M. horni are easily separable from those of other eriococcid firstinstar nymphs known from the Neotropics in having only setose dorsal setae (all other South American eriococcid first-instar nymphs have some spinose dorsal setae). In addition, the first-instar nymph of M. horni has: (i) 6 segmented antennae; (ii) exceptionally long microtubular ducts restricted to the dorsum and margin; (iii) cupolate-shaped marginal spinose setae; (iv) no cruciform pores; (v) single loculate pores laterad to each spiracle; and (vi) anal lobes unsclerotised and not differentiated.
description: Published as part of Hodgson, Chris & Miller, Dug, 2010, A Review of the Eriococcid Genera (Hemiptera: Sternorrhyncha: Coccoidea) of South America 2459, pp. 1-101 in Zootaxa 2459 (1) on page 61, DOI: 10.11646/zootaxa.2459.1.1, http://zenodo.org/record/5313324