Lepidobrya mawsoni ( Tillyard, 1920 )

Zhang, Feng, Greenslade, Penelope & Stevens, Mark I., 2017, A revision of the genus Lepidobrya Womersley (Collembola: Entomobryidae) based on morphology and sequence data of the genotype, Zootaxa 4221 (5), pp. 523-536 : 525-529

Lepidobrya mawsoni ( Tillyard, 1920)

Figs 1‒39

Entomobrya mawsoni Tillyard, 1920

Type locality. Garden Cove , Macquarie Island, Australia.

Type material. Australian Museum, Sydney, holotype (AAE 12I2 on slide) and paratypes (AAE 12‒13 on slides and C 24 in alcohol).

Material examined. Three females and one male on slides and three in alcohol, Australia: Macquarie Island : Razorback Ridge, 54.503°S, 158.933°E, 22.viii.2010, Peter Hudson leg. One slide and one in alcohol depsited in NJAU and others in SAMA. Additional material examined on slides (all Macquarie Island): Buckles Bay, 1931 ; North Arm , 7.xi.1972 ; Isthmus , 11.iii.1975 ; Isthmus , 17.xi.1977 ; Plateau , xii.1986 ; Buckles Bay , 5.i.1987 .

Redescription. Body length up to 3.00 mm. Background colour yellow in alcohol. Violet pigment on antennae and legs and dark blue pigment on body. Antennae gradually becoming darker from base to apex. Eye patches dark with a transverse band between them ( Fig. 1 ). Transverse bands on posterior half of Abd. II, Abd. III, distal margin of Abd. IV, and Abd. V. Lateral stripes on thorax and Abd. IV. Irregular longitudinal patches on median part of Th. II‒Abd. I. Distal parts of trochanters, femora and tibiotarsi pigmented ( Figs 1‒3 ). Scales brown, narrow, pointed with short ribs ( Figs 3‒9 ); scales in the posterior row along margin of Th. II‒Abd. III larger than anterior ones ( Figs 3‒8 ); on Abd. IV, only few chaetae in the posterior row along margin transformed into scales ( Fig. 9 ); a row of long, thin chaetae along posterior margin of Abd. V ( Fig. 10 ); scales ventrally on manubrium ( Fig. 11 ) and dens ( Fig. 13 ) narrower than those on body. Scales on Ant. I‒II ( Fig. 14 ), legs, ventral side of manubrium and dens, and dorsal side of head and terga but absent from Ant. III‒IV, ventral tube and dorsal side of manubrium ( Fig. 12 ) and dens.

Antenna 2.03‒2.41 times as long as cephalic diagonal. Antennal segment ratios as I: II: III: IV = 1: 1.55‒1.75: 1.50‒1.65: 2.23‒2.60. Smooth, spiny mic at base of antennae: three dorsal ( Fig. 14 ), four ventral ( Fig. 15 ) on Ant. I, one internal, one external and two ventral on Ant II. Ant. II distally with 2‒3 rod-like S-chaetae. Ant. III organ with two rods and three guard chaetae ( Fig. 16 ). Antennal apical bulb absent.

Eyes 8+8, G and H smaller. Labral margin with four simple papillae. Labral intrusion U-shaped. Prelabral and labral chaetae 4/5, 5, 4; prelabral ones ciliate; median three chaetae of the first row longer than lateral ones ( Fig. 17 ). Clypeal chaetae ciliate with about facial 25 chaetae ( Fig. 18 , after Zhang et al., 2016a). Dorsal cephalic chaetotaxy with five antennal (An), five(six) median (M) and eight sutural (S) mac; a pair of mac between anterior and median mac and a sixth mac in the median row present in one specimen; interocular chaetae seven or eight ( Fig. 19 ). Mandibles with 4/5 (left/right) teeth. Subapical chaeta of maxillary outer lobe slightly larger than apical one; three hairs on sublobal plate; all smooth. Labial papillae A‒E with 0, 5, 0, 4, 4 guard chaetae, respectively; tip of lateral process of labial palp not reaching apex of labial papilla ( Fig. 20 ). Labium with five and 8(9) chaetae on mentum and submentum ( Fjellberg 1999), respectively; chaeta R 0.70‒0.75 times of M in length. Chaetae posterior to labium ciliate. Cephalic groove with 12‒16 ciliate chaetae ( Fig. 21 ).

Metatrochanteral organ with 35¯44 smooth spine-like chaetae ( Fig. 22 ). Inner differentiated tibiotarsal chaetae finely ciliate ( Fig. 34 ). Tibiotarsi distally with 10 ciliate chaetae in a whorl. Unguis with two inner, one outer and two lateral teeth; unpaired inner teeth absent. Unguiculus truncate with one inner and one outer teeth. Tenent hairs weakly ciliate with tip clavate and subequal to unguis in length ( Fig. 23 ). Abd. IV 4.89‒6.43 times as long as Abd. III along dorsal midline. Ventral tube anteriorly with 32‒49 ciliate chaetae, two of them much longer and thicker than others ( Fig. 24 ); posteriorly with two apical smooth and about 90 proximal ciliate chaetae; each lateral flap with five smooth and eight ciliate chaetae ( Fig. 25 ). Tenaculum with 4+4 teeth and corpus with one large chaeta. Male genital plate with seven pairs of projections and internally with a pair of small chaetae ( Fig. 26 ). Manubrial plaque with two pseudopores and 17‒18 ciliate chaetae ( Fig. 27 ). Manubrium ventrally with about 40 + 40 distal scale-like chaetae or extremely narrow scales ( Figs 28 , 35 ). Dens without spines; distal smooth part 0.70 times as long as mucro. Mucro bidentate, basal spine short with tip reaching apex of subapical tooth ( Fig. 29 ).

Th. II with 7(8) medio-medial, three (m4, m 4i, m4p) medio-sublateral, 23‒25 posterior mac; p4 and p5 as mac; sens inner to ms. Th. III with 22 mac; m 5i, m5p, a 6i and m 6i as mac ( Fig. 30 ). Abd. I with 6(5, 4) mac (a2‒3, m2‒4, m4p); a2 and a3 sometimes as mic; sens inner to ms. Abd. II with five (a2, a3, m3, m3e, m3ep) central and one (m5) lateral mac. Abd. III with one (m3) central and four (am6, pm6, p6, m7a) lateral mac ( Fig. 31 ). Abd. IV with 22¯27 central, 16¯22 lateral mac with their homology difficult to determine ( Fig. 32 ). Abd. V with three sens ( Fig. 33 ). Tergal ms as 1, 0|1, 0, 1, 0, 0; sens as 2, 2|1, 2, 2,?, 3 ( Figs 18 , 30‒33 , 36, 37 ). Small scales present around abdominal bothriotricha ( Figs 37‒39 ).

Distribution. Australia ( Macquarie Island); New Zealand (Campbell Island, Auckland Islands).

Remarks. Types were not examined because the specimens having the same unique pigmentation accurately described by Tillyard have been collected for many times in Macquarie Island; the other two entomobryid species in this island, Lepidocyrtus cyaneus cinereus Folsom and Lepidosira terraereginae (Ellis & Bellinger) , distinctly differ from Lepidobrya mawsoni . Lepidobrya mawsoni is similar to L. thalassarchia and L. violacea from Campbell Island and L. aurantiaca from Auckland Island in having two inner teeth on unguis, truncate unguiculus with an outer tooth, and pointed scales even on dens. It differs from them by its unique colour pattern. Pigment patches are very stable in examined specimens even in those weakly pigmented individuals ( Fig. 40 ). Womersley (1937) and Salmon (1949) mentioned a small antennal apical knob, which was never observed in our specimens. More details cannot be compared before the types or topotypes of the New Zealand species are examined. Greenslade (1994) synonymised L. aurantiaca Salmon, 1949 from Auckland Islands with L. mawsoni but did not give reasons. DNA barcodes from Adams Island provide potential support for this synonymy (see comments below).

Figures

FIGURE 40. Neighbor-Joining phylogram (below) and pairwise distance matrix (above) using patristic (P) distance for haplotypes of Lepidobrya mawsoni from Macquarie I. (MI) and Auckland Islands (Adams I.; ADI), and Lepidobrya spp. from Campbell I. (CI) and Antipodes I. (AI). Inset images: Lepidobrya sp. from Adam I. (left) and L. mawsoni from Macquarie I. (right). Codes, haplotypes (number of sequences with same haplotype in parentheses), locations and GenBank accessions refer to Table 1.

FIGURES 1 ‒ 3. Colour pattern of two individuals in Lepidobrya mawsoni. Scale bars: 1 mm.

FIGURES 4 ‒ 9. Scales / chaetae in the posterior row along tergal margin in Lepidobrya mawsoni, left side except Fig. 9. 4, Th. II; 5, Th. III; 6, Abd. I; 7, Abd. II; 8, Abd. III; 9, Abd. IV. Scale bars: 4 ‒ 8, 50 µm; 9, 120 µm.

FIGURES 10 ‒ 15. Lepidobrya mawsoni. 10, chaetae on Abd. V (right side); 11, ventral scales on manubrium; 12, dorsal side of manubrium; 13, dental scales; 14, base of left Ant. I, dorsal view; 15, base of left Ant. I, ventral view. Scale bars: 50 µm.

FIGURES 16 ‒ 24. Lepidobrya mawsoni. 16, Ant. III apical organ; 17, labrum; 18, clypeal chaetae; 19; dorsal cephalic chaetotaxy; 20, right labial papillae E, dorsal view; 21, labial and postlabial chaetae; 22, trochanteral organ; 23, hind claw, posterior view; 24, anterior face of ventral tube. Symbols representing chaetal elements used in this paper are as follows: large circle, macrochaeta; small circle, microchaeta; cross, bothriotrichum; circle with a slash, pseudopore.

FIGURES 25 ‒ 29. Lepidobrya mawsoni. 25, posterior face and lateral flap of ventral tube; 26, male genital plate; 27, manubrial plaque; 28, distal part of manubrium ventrally; 29, mucro.

FIGURES 30 ‒ 33. Tergal chaetotaxy in Lepidobrya mawsoni, left side. 30, thorax; 31, Abd. I ‒ III; 32, Abd. IV, only partial sens illustrated; 33, Abd. V.

FIGURES 34 ‒ 39. Lepidobrya mawsoni. 34, inner differentiated tibiotarsal chaetae; 35, distal part of manubrium ventrally; 36, S-chaetae on Abd. I; 37 ‒ 39, bothriotricha and accessory scales; 37, Abd. II laterally; 38, Abd. III laterally; 39, Abd. IV.