Bambusaspis transversa Łagowska & Martin, 2015

Łagowska, Bozena, Martin, Jon H. & Hodgson, Chris J., 2015, A new species of Bambusaspis Cockerell (Hemiptera: Sternorrhyncha: Coccomorpha) colonising bamboo in Malaysia, Zootaxa 4006 (1), pp. 128-142 : 129-140

Bambusaspis transversa Łagowska & Martin sp. n.

Type material studied: Holotype adult female, WEST MALAYSIA, Negeri Sembilan. Senawang, on Bambusa tuldoides (Poaceae) , March 2011, J.H. Martin #8509 ( BMNH). Paratypes: 35 slides with 24 adult females; 27 first-instar nymphs; 12 second-instar female; 21 second-instar males; 4 prepupae; 8 pupae and 12 adult males (mainly good-to-fair condition), same bamboo thicket as holotype, dates between November 2010 and March 2012 ( BMNH, USNM, MNHN). Other material: Dry specimens attached to host plant, data as for paratypes ( BMNH).

Name derivation. The species name transversa is from the Latin transversus, meaning crosswise or transverse, referring to the transverse rows of large 8-shaped pores medially on the dorsum of the adult female.

Adult female ( Fig. 1; Plate 1). Described from twelve specimens in fair to good condition.

Unmounted material. Elongate oval. Dried material pale brown but live specimens almost certainly pale green. Dorsum with a median band of very long glassy wax filaments plus a few shorter ones elsewhere. Margin with a rim of white wax filaments. Remainder of dorsum covered in a glassy test.

Mounted material. Body of young female oval, widest in thorax; anal lobes short; body of old, possibly postreproductive, females tending to be almost round, with several posterior segments of abdomen retracted into body and covered by dorsum; in these specimens, the anal lobes are barely apparent. Body 1.7–3.5 mm long, 1.1–3.4 mm wide.

Dorsum with an almost complete marginal row of medium-sized 8-shaped pores, not quite reaching anal lobes posteriorly; with 149–185 pores per side, each pore V-shaped and 9.5–13.0 µm long, 6–8 µm wide. Larger 8- shaped pores, each 21–29 µm long, 10–22 µm wide, in a submarginal row, pores arranged segmentally on abdomen but more randomly on thorax and head; and in a broad medial band, with about 7–11 transverse groups, each group with 1–15 pores; pores towards outside of each band smaller. Simple disc pores of 2 sizes, a smaller pore, each 2.5– 3.5 µm wide, in transverse segmental bands on abdomen and in groups associated with large 8-shaped pores both medially and submarginally, plus a larger pore, each about 3.5–4.5 µm wide, present near margin. Minute 8-shaped pores, each 3.0–3.5 x 2.5–2.8 µm wide, present amongst simple pores, but most abundant submedially between submarginal and medial large 8-shaped pores. Tubular ducts present throughout, each 35–44 µm long, 4.0–6.5 µm wide. Caudal tubes present, each membranous and about 8 µm wide. Anal lobes short, with a shallow anal cleft; each lobe with a long apical seta 75–82 µm long; plus an outer spinose seta and 2 inner spinose setae between each long seta and anus, each about 13–14 µm long. Anal ring with a loose row of pores and 6 setae, each seta 44–50 µm long.

PLATE 1. Adult female Bambusaspis transversa Łagowska & Martin. Dried specimen on stem of Bambusa tuldoides , West Malaysia.

Venter. Quinquelocular pores, each 2.5–4.0 µm wide, in an almost complete marginal row; also in a radial group of 10–25 pores between each antenna and margin; larger quinquelocular pores, each 3.0–4.5 µm wide, present in broad stigmatic bands, each 7–9 pores wide; each anterior band with 80–100+ pores and each posterior band with 55–90+ pores respectively. Microducts, each 2–3 µm long, 1.5–3.0 µm wide, in transverse bands medially on thorax and abdomen, and scattered in a broad band submarginally, extending from head to posterior abdominal segments. Multilocular pores present in a semi-circle of 5–8 pores around genital opening, each pore 7– 8 µm wide with mainly 10 loculi. Setae few, with 2 pairs just posterior and one pair anterior to vulva; also with pairs in preceding 3 abdominal segments and in a submarginal row of at least 8 setae on each side of thorax and abdomen.

Antennae one segmented, each 16.0–18.5 µm long, and about 16 µm wide at base; with 5 fleshy setae. Clypeolabral shield 196–257 µm long, 234–241 µm wide. Labium very small, 35–44 µm long, 52–73 µm wide; without setae. Spiracles positioned submedially, width of spiracular peritremes: anterior 50–57 µm, posterior 44– 49 µm.

Comment. The main character-states that appear to diagnose the adult female of B. transversa are: (i) the transverse lines or bands of large 8-shaped pores medially on the dorsum; (ii) the sparse submarginal line or band of large 8-shaped pores on the dorsum; (iii) almost complete marginal line of smaller 8-shaped pores; (iv) the presence of minute 8-shaped pores on the dorsum; (v) the radial band of quinquelocular pores extending from each antenna to the margin; (vi) the very broad stigmatic bands, each with perhaps 100+ quinquelocular pores; (vii) the relatively few multilocular disc-pores around the vulva; (viii) the four pairs of setae on the apex of the abdomen; (ix) the very broad band of ventral microducts, and (x) the six anal ring setae. For further comment, see Discussion.

First-instar nymph ( Fig. 2). Described from nine specimens in fair to good condition.

Mounted material. Body elongate, widest in thorax; length 361–568 µm, width 150–245 µm; with a shallow anal cleft.

Dorsum and margin. Dorsal surface with large 8-shaped pores, each slightly V-shaped, arranged in a single marginal row and in 2 medial rows; pores in marginal row, each 8.0–9.5 µm long, 3–4 µm wide, all lying lengthwise along margin, with 13 pores on each side; pores in medial rows larger, each 12.5–15.0 µm long, 8.5–9.0 µm wide, with 10 pores in each row. Simple pores present in a submedial longitudinal line, each line with 11 or 12 pores arranged segmentally on abdomen, 3 pores on thorax and 2 on head. Minute 8-shaped pores absent. Setae slender, each 5.5–6.0 µm long, with 3 pairs on either side in cephalic region; other setae absent. Anal lobes each with an apical seta, 60–74 µm long, 1 stout seta on inner margin 9.5–11.0 µm long, and a similar seta on outer margin, about 6 µm long. Anal ring circular, about 6 µm wide, with 1 row of pores and 6 fleshy setae, each 5.5–6.0 µm long.

Venter. Microducts, each 2–3 µm wide, in a submarginal line, with 2 or 3 pores in cephalothorax and 1 pore in each abdominal segment. Ventral setae: with 2 pairs of setae between antennae, each 20–25 µm long, and a line of minute submarginal setae on abdomen, one seta per segment. Antennae well developed, each 6 segmented, total length 64–79 µm; segment lengths: I 12.0–13.5; II 9–13; III 14.5–19.5; IV 9.0–13.5; V 6.5–9.5; and VI 12.0–15.5 µm; setal distribution as follows: scape 1 hair-like seta, pedicel 2 long hair-like setae; III 0 setae, IV and V 1 hairlike seta and apical segment (VI) with 2 very long setose setae, longest 49.5–61.5 µm long, plus 3 short setose setae and 3 (quite long) fleshy setae. Clypeolabral shield 42–52.5 µm long, 25.5–8.5 µm wide. Labium oval, 27.5–29.0 µm long; 24–29 µm wide, with 2 pairs of slender setae. Spiracular peritremes each about 4.5 µm wide, with 1 trilocular pore and 1 quinquelocular pore in each stigmatic furrow.

Legs 5 segmented, subequal in length, prothoracic 112–126 µm long, mesothoracic 121–129 µm long, and metathoracic 121–132 µm long; claws slender, each 11–13 µm long, without a denticle; claw digitules each 11.5– 14.5 µm long; tarsal digitules on meso- and metathoracic legs each 22.5–23.5 µm long, but with only a single long digitule on prothoracic legs (a minute second digitule probably present).

Comment. The main character-states that appear to diagnose the first-instar nymph of B. transversa are: (i) the two medial lines of 10 large 8-shaped pores; (ii) the marginal line of 13 large 8-shaped pores on each side; (iii) the submedial line of simple pores on the dorsum; (iv) the three pairs of setae on the apex of the abdomen; (v) each stigmatic band with one quinquelocular and one trilocular disc-pore; (vi) labium with two pairs of setae; (vii) each antenna with setae on all segments bar segment III; and (vii) two pairs of interantennal setae. For further comment, see under Discussion below.

Second-instar female ( Fig. 3). Described from ten specimens in fair to good condition.

Mounted specimen. Body oval, 710–1029 µm long, 330–655 µm wide. Anal lobes small.

Dorsum and margin. Medium-sized 8-shaped pores in a marginal row, each pore 9.5–11.5 µm long, 5 µm wide, in line of 82–90 on each side; also rather larger 8-shaped pores in a medial band, each 13.5–22.0 µm long, 11.5–16.5 µm wide, but with outermost pores smaller, with a total of 27–33 pores arranged in 11 groups of 2 or 3 on cephalothoracic and abdominal segments; also occasionally with a smaller 8-shaped pore, each about half size of larger pores, between or just lateral to each group of larger pores. Simple pores, each about 2.5 µm wide, in 3 longitudinal lines on each side: a submarginal line of 11–13 pores, a submedial line of 10 or 11 pores just lateral to larger 8-shaped pores, and a line of 6 pores lying between medial 8-shaped pores and margin, extending from head to anterior abdominal segments; a single pore generally also present on dorsal surface of each anal lobe. Minute 8- shaped pores, each about 3 µm long, sparse, more or less randomly placed throughout but often apparently associated with a simple pore. Anal lobes each with an apical seta 55–61 µm long, plus an outer spinose seta and 2 inner setae, each 6.5–8.0 µm long. Anal ring well developed, semicircular, 15.5–17.0 µm wide, with a loose row of pores and 6 fleshy setae, each 29.5–33.0 µm long.

Venter. Venter with a marginal band of quinquelocular pores, each 2.5–3.0 µm wide, in a single row of 62–68 on each side, and in bands of 4–7 mainly quinquelocular pores between spiracles and margin. Microducts, each 2.0–2.5 µm wide, in submarginal lines or bands of 23–35 pores on each side of body, and also in submedial lines, each line probably one per segment. Setae few: with a pair on last abdominal segment (VIII), a minute seta on segment VII and 5 or 6 pairs submarginally in preceding abdominal segments and one in thorax. Legs absent. Antennae one segmented, circular, 8.0–9.5 µm wide, with 3 long setae, longest 11.5 µm long, and 3 slender setae. Clypeolabral shield 80–94 µm long, 64–70 µm wide. Labium circular, 31–38 µm long, 34–44 µm wide; without labial setae. Width of each spiracular peritreme 12–15 µm wide.

Comment. See under second-instar male.

Second-instar male ( Fig. 4). Described from 13 specimens in fair to good condition.

Mounted specimens. Body elongate, widest in cephalothorax; 974–1174 µm long, 439 –595 µm wide.

Dorsum and margin. Eight-shaped pores in 3 rows, as follows: moderate-sized pores in a marginal row one pore wide, each pore 9.0–10.5 µm long, 4–5 µm wide, with a total of 79–89 pores on each side; a submedial line of slightly larger pores, each 14.0–17.5 µm long, 9.5–12.0 µm wide, with 1 pore on head, 1 or 2 pores on thorax and 2 or 3 pores on abdomen; and still larger 8-shaped pores, each 18.5–22.5 µm long, 11.5–13.5 µm wide, in a broad medial band with 10 or 11 groups of 2 or 3 pores totalling 28–32 pores; occasionally smaller pores present between medial groups of large 8-shaped pores, each about 13 µm long. Tubular ducts, each 21.5–25.0 µm long, 2.5–4.0 µm wide, scattered over dorsum, mainly arranged in segmental bands on abdomen. Simple pores, each about 2 µm wide, arranged in a submarginal row of 11–13 on each side and in a line lateral to each medial group of large 8- shaped pores; simple pores also present in a line of 6 pores between medial 8-shaped pores and margin, with 1 on head, 2 on thorax and 3 on abdomen; also with a single pore on dorsal surface of each anal lobe. Minute 8-shaped pores, each about 2.5–3.0 µm wide, present rather randomly as single pores more or less associated with some submedial and submarginal simple pores. Anal lobes each with an apical seta about 52 µm long, an outer spinose seta and 2 inner setae, each about 7–7.5 µm long. Anal ring well developed and semicircular, 15.5–17 µm wide, with a loose row of pores and 6 fleshy setae, each 29.5–33 µm long.

Venter. Quinquelocular pores, each 2.5–3.0 µm wide, present in a marginal row of 64–70 on each side; most pores quinquelocular, but occasionally some trilocular; also with 2–5 mainly quinquelocular pores between each spiracle and margin. Microducts in submarginal rows of 23–38 pores on each side and in submedial rows of 11 or 12 pores. Leg-stubs present submedially on thorax. Submarginal setae present in a line of about 10 on each side. Antennae one segmented, plate-like, each 8.0–9.5 µm wide, with 3 long fleshy setae, longest 9–12 µm long, plus one or 2 short seta about 4.0 µm long. Clypeolabral shield about 82 µm long, 63 µm wide. Labium nearly circular, about 32 µm long and 36 µm wide; without labial setae. Spiracular peritremes each about 8–10 µm wide.

Comment. Superficially, second-instar male and second-instar female nymphs are similar because their pore distribution is much the same. However, they differ as follows (character-states for second-instar females in brackets): (i) dorsal tubular ducts frequent throughout dorsum (absent); (ii) a few 8-shaped pores present submedially on dorsum (absent); and (iii) leg stubs present (absent). In addition, second-instar males are slightly larger and appear broadest across the prothorax whereas the second-instar females are broadest about the metathorax.

Prepupa ( Fig. 5). Described from three specimens in fair condition.

Mounted specimens. Body 1.0– 1.1 mm long, 0.4–0.5 mm wide. Dermal nodules present medially on head, thorax and abdomen on both dorsum and venter.

Dorsum. Wing buds 106–200 µm long. Setae absent apart from groups of 3 small blunt incipient glandular pouch setae on each side just anterior to genital segments, median seta much longest.

Venter. Antennae 9 segmented, each 163–200 µm long. Setae restricted to minute pairs of ventral abdominal setae on segments V–VII and single pleural setae on each abdominal segment. Spiracles without associated pores or furrows. Legs 5 segmented, hind leg 120–166 µm long. Genital segment sclerotised.

Pupa ( Fig. 6). Described from six specimens in fair to good condition.

Mounted specimens. Body 1.0– 1.1 mm long, 0.4–0.5 mm wide. Dermal nodules present medially on head, thorax and abdomen on both dorsum and venter.

Dorsum. Wing buds about 206–426 µm long. Setae restricted to 1 longer seta (about 8 µm long) and 2 very short (about 1 µm long) blunt incipient glandular pouch setae on each side anterior to genital segments.

Venter. Setae restricted to minute ventral abdominal seta on segments IV–VII and single pleural setae on abdominal segments. Antennae 10 segmented, each 376–455 µm long; apical segment with a minute conical protuberance and segments VII and IX both with a pore-like structure. Spiracles without associated pores or furrows. Legs 5 segmented, each distal segment with a minute conical protuberance; hind legs 378–441 µm long. Genital segment sclerotised.

Note. the pore-like structures on antennal segments VII and IX probably represent the large antennal bristles on these segments in the adult male.

Adult male ( Fig. 7). Described from six specimens in good condition.

Mounted material: small, total body length about 0.97–1.18 mm; robust; antennae about half total body length, with some very long setae on 3 segments; body with very few setae, fleshy setae (fs) only present on limbs, fairly obviously different from hair-like setae (hs); length of setae on antennae more than width of antennal segments. Wings about 3/4 total body length and about 1/2 as wide as long.

Head: rather triangular in dorsal view; length 155–160 µm, width across genae 195–200 µm. Median crest very broad posterior to antennae, strongly reticulated, each reticulation without additional inner ridges, reticulations extending laterally onto ocular sclerite; with 2 sclerites posteriorly lying diagonally to mid-line, representing postoccipital ridge; with 0 or 1 dorsal head setae. Mid-cranial ridge absent dorsally; ventral ridge well developed, extending posteriorly to level with anterior margin of ventral simple eyes; with well-developed lateral arms; ventral mid-cranial ridge with a lightly reticulated border posteriorly; with 0 or 1 ventral mid-cranial ridge setae. Genae without polygonal reticulations; genal setae and genal protuberance absent. Simple eyes: with 2 pairs of round, simple eyes; dorsal eyes marginally smaller than ventral eyes: dorsal eyes 35–40 µm wide; ventral eyes 48–55 µm wide. Ocelli absent. Ocular sclerite sclerotised and polygonally reticulated throughout, each reticulation rather small, without inner ridges. Preocular ridge with ventral arm extremely short or absent; dorsal arm extending posteriorly to level with dorsal margin of dorsal simple eye. Postocular ridge strongly developed, extending dorsally just posterior to dorsal eyes and then posteriorly to behind post-occipital ridges; appearing to touch each dorsal simple eye. Dorsal ocular setae absent. Ventral head setae: with about 11–13 on each side, including about 4 pairs between ventral eyes; ventral head setae extending laterally almost to dorsal eyes; without setae posterior to ventral eyes. Preoral ridge possibly absent or poorly developed. Cranial apophysis elongate, extending anteriorly between ventral eyes; about 50 µm long.

Antennae: 10-segmented and filiform; 525–550 µm long (ratio of total body length to antennal length 1:0.5); with an extremely long seta on segments VII, IX and X. Scape: 33–35 µm long, 40–44 µm wide, with 7–10 fs + 0 or 1 hs. Pedicel: length 25–27 µm, width 30–32 µm; with a few concentric ridges and 7–10 fs + 1 hs. Segments III– X all about 18 µm wide; lengths of segments (µm): III: 68–70; IV: 75–78; V: 63–65; VI: 53–63; VII: 50–60; VIII: 50–52 and IX: 50–60. Setae: hair-like setae each 13–15 µm long, long fleshy setae each about 25–40 µm long; approximate number of setae per segment: III: 7–9 fs (sensilla basiconica not noted) + 0 hs; IV: 12 or 13 fs + 2 hs; V: 14–16 fs + 2 hs; VI: 14 or 15 fs + 1–3 hs; VII: 9 fs + 1–4 hs + 1 extremely long antennal bristle, 80–110 µm long; VIII: 9 fs + 0–2 hs; IX: 10–12 fs + 0–2 hs + 1 long antennal bristle, 95–100 µm long. Segment X: length 50– 55 µm; not constricted apically; with usually 1 (occasionally 2) capitate setae, 4–9 fs + 2 very long antennal bristles; with a single sensilla basiconica near apex.

Thorax. Prothorax: pronotal ridge well developed; with a narrow, striated, lateral pronotal sclerite; without lateral pronotal setae. Medial pronotal setae, post-tergites and post-tergital setae absent. Sternum not sclerotised but with a few fine microridges extending anteriorly; transverse ridge weak; median ridge strongly sclerotised, extending anteriorly to between procoxae (length about 80–85 µm); without prosternal setae. Anteprosternal and antemesospiracular setae absent.

Mesothorax: prescutum 74–80 µm long, 135–140 µm wide; sclerotised, without distinct nodulations; prescutal ridges and prescutal suture well developed. Scutum: median membranous area 125–140 µm wide, about 62 µm long, bounded laterally by strongly sclerotised margins; scutal setae absent; surface of membranous area very lightly reticulated; lateral margins of scutum sclerotised but not reticulated. Scutellum 155–160 µm wide, 70 µm long; with a large foramen; without scutellar setae. Basisternum 200–205 µm wide, 90–110 µm long; with a strong median ridge; bounded anteriorly by a moderately strong marginal ridge and posteriorly by a strong precoxal ridges; without basisternal setae; lateropleurite apparently quite broad but rather unsclerotised, extending to subepisternal ridge; lateropleurite without an extension from marginal ridge anteriorly; furca well developed, broad basally, posterior half of arms parallel but diverging anteriorly; each arm extending anteriorly to about 2/3rd of distance to marginal ridge. Mesopostnotum and postnotal apophysis well developed. Area bounded anteriorly by scutellum and laterally and posteriorly by mesopostnotum not reticulated. Mesepisternum not reticulated; subepisternal ridge well developed. Postalare not reticulated anteriorly; without postalare setae. Mesothoracic spiracle with peritreme 20–22 µm wide. Postmesospiracular setae absent. Tegula apparently membranous, with 5– 8 tegular setae on each side.

Metathorax: without metatergal setae. Dorsospiracular setae absent. Dorsal part of metapleural ridge absent; ventral part of metapleural ridge well developed but short; episternum probably unsclerotised, without postmetaspiracular setae. Metepimeron sclerotised but without setae. Antemetaspiracular setae absent. Metathoracic spiracle: width of peritreme 25–27 µm. Metasternum possibly lightly sclerotised. Anterior metasternal setae and posterior metasternal setae absent.

Wings: hyaline, 775 µm long, 375 µm wide (ratio of length to width 1:0.48; ratio of total body length to wing length 1:0.71); alar lobe and alar setae absent; wing venation normal. Hamulohalteres absent.

Legs: metathoracic legs possibly marginally longest. Coxae lengths (µm): I: 70–83; II: 78–83; III: 86–90 long; setae of coxa III: about 20–25 fs + 1 hs; long apical setae on each coxa not differentiated. Trochanter + femur: I: 194–203; II: 200–205; III: 210–224 µm long; trochanter III elongate and broadest distally, strongly overlapping femur; with about 9 fs + 2 hs; long trochanter seta undifferentiated; femur III with many setae, mainly fs. Tibia: I: 145–157; II: 140–150; III: 155–165 µm; tibia III with many setae, mainly fs, none becoming spur-like on distal third of leg; without apical spurs. Tarsi: I: 150–158; II: 155–158; III: 165–175 µm long (ratio of length of tibia III to that of tarsus III 1:1.06); tarsus III with many setae, those on distal 2/3–3/4 spur-like; tarsal spurs undifferentiated; tarsal campaniform sensilla present; tarsal digitules fine, with small apical knobs, shorter than or subequal in length to claw. Claws quite long and thin, rather longer than width of tarsi, slightly curved, without a denticle, not held at right-angles to tarsus; length: III 20–22 µm; claw digitules fine, with small apical knobs, shorter than or subequal to length of claw.

Abdomen: segments I–VII: tergites unclerotised but distinctly nodulated medially; sternites of all segments lightly sclerotised, without obvious oval membranous areas in inter-segmental membranes. Caudal extension of segment VII absent. Dorsal setae absent. Pleural setae: dorsopleural setae: II–VII 1 hs on each side; ventropleural setae absent. Ventral setae (totals): II–V absent; VI & VII 1 pair of short hs.

Segment VIII about 40 µm long, 60 µm wide; caudal extensions small and rounded, each with 3 pleural setae, one significantly longer, 40–50 µm long, others short; tergite and sternites lightly sclerotised; sternite sometimes with a pair of hs. Glandular pouches and glandular pouch setae absent. Anus present in intersegmental membrane between VIII and penial sheath dorsally.

Genital segment. Penial sheath about 225–245 µm Iong, 60–70 µm wide, narrowing quite sharply about 1/3rd along length (anterior part) and then more gradually to a fine apex (ratio of total body length to penial sheath length 1:0.2). Basal membranous area present just anterior to basal rod; basal rod 35–40 µm long, not extending down aedeagus. Aedeagus long and slowly tapering, 205–225 µm long; apex about level with apex of penial sheath. Penial sheath setae: with 2 pairs of longer setae ventrally lateral to basal rod and 4 or 5 smaller setae on each side; also with a group of small sensilla near apex.

Comment. To-date, the adult males of only two species of Asterolecaniidae have been fully described and illustrated ( A. proteae Giliomee & Munting (Giliomee & Munting 1968) and Grammococcus adetocorymbus Miller & Lambdin (Miller & Lambdin 1978), although the latter authors also partially described the adult male of G. co r y m b u s Miller & Lambdin. In addition, Hodgson (unpublished) has studied the males of Bambusaspis delicatum (Green) , B. longa (Green) , Hsuia cheni Borchsenius and Asterolecanium petrophilae (Fuller) . Of these species, those currently included in Bambusaspis can be easily separated from all others except H. cheni by: (i) presence of exceptionally long antennal bristles on several antennal segments (otherwise absent), and (ii) in having 10-segmented antennae (9-segmented on the other species). The adult males of the three Bambusaspis species can be separated by the distribution of the long antennal bristles: B. delicata on segments V, VII, VIII, IX and X; B. longa on segments IV, VII and X, and B. transversa on segments VII, IX and X. The adult male of H. cheni also has ten-segmented antennae and a few long antennal bristles (on segments VII and X) but differs from the three Bambusaspis species in have a very short and broad penial sheath. Too few adult males have been studied to-date to know the significance of these differences.