The systematic status of the genus Summersiella Gonzalez is reviewed and a revised definition is proposed. A new species, Summersiella camphorae, from the leaves of camphor tree (Cinnamomum camphora) in Fujian Province of China, is described and illustrated. This new species is distinguished from the only known species, Summersiella coprosmae (Wood), by having an apparently sclerotized hexagonal central hysterosomal shield with five pairs of setae; by having much shorter dorsal setae (ve not exceeding base of sci); by the following ratios: vi/vi-vi = 0.7, ve/ve-sci = 1.0; and by the length of solenidion w on tarsus I (19–21 µm).
The little known stigmaeid genus Summersiella was erected by Gonzalez (1967), based on Summersiella ancydactyla Gonzalez, 1967 from New Zealand. Two years later Meyer (1969) considered Summersiella a synonym of Pseudostigmaeus because the characters used by Gonzalez (1967) for separating Summersiella from related genera (i.e. palptarsus bending mesad at its basal third and the basis of capitulum being broad) were not of generic value, and because the genus was monotypic. However, Wood (1971) confirmed its generic status after detailed studies on the palptarsus, dorsal shields, setation of coxae and leg empodia of S. coprosmae, which he first placed in Stigmaeus, but later considered to be a senior synonym of Summersiella ancydactyla Gonzalez, 1967. So far, this is the only known species of Summersiella and it is distributed only in New Zealand. A new species, Summersiella camphorae, from the leaves of camphor tree [(Cinnamomum camphora (L.)] in Fujian Province of China, is described and illustrated in this paper. Due to the discovery of this second species, a revised definition of the genus is provided and the taxonomic position of Summersiella is discussed.
Genus Summersiella Gonzalez
Pseudostigmaeus, Meyer, 1969: 245; in part.
Female. Idiosoma oval in dorsoventral view. Chelicerae separate. Palpi relatively robust; tibial claw subequal in length to palptarsus; accessory claw developed, spiniform. Palptarsus basally angled; basal seta bp well developed, spinelike; terminal eupathidia basally fused and halfway separated to three long prongs. Fundamental setation from palptrochanter to palptarsus on adult: 0, 3, 2, 2 +1 claw+1 accessary claw, 3 + 1 spinelike seta + 1ω; + 1 subterminal spinelike eupathidium + 3 basally fused eupathidia. Subcapitulum with two pairs of setae (m and n), both posterolaterad of pharynx. Propodosoma covered with a triangular shield, which bears one pair of eyes, one pair of feebly developed postocular bodies and four pairs of setae (vi, ve, sci, sce); sci posteromediad of sce. Hysterosomal shield weakly or well sclerotised. Humeral shields vestigial, each with one seta (c2). Intercalary shield plateletlike, each with one seta (f1). Suranal shield (H) integral, bearing two pairs of setae (h1 and h2). Endopodal shields absent. Idiosomal venter with three pairs of ventral setae (1a, 3a and 4a), and three pairs of aggenital setae (ag1, ag2 and ag3). Genital and anal openings contiguous, with one pair of genital setae (g1) and three pairs of pseudanal setae (ps3, ps2 and ps1) on adult female. Leg tarsal claw well developed and basally enclosed with a membranous arolium. Empodium rodlike, arising from arolium and bearing three Y-shaped tenent hairs. Fundamental setation of legs I-IV on adult female: coxae 2, 2, 2, 2; trochanters 1, 1, 2, 1; femora 6, 4, 3, 2; genua 3 + 1κ;, 2, 0, 1; tibiae 5 + 1pφ;, 5 + 1φ;p, 5 + 1φ;p, 5 + 1φ; p; tarsi 13 + 1ω;, 9 + 1ω;, 7 + 1ω;, 7 + 1ω;.
The basally angled palptarsus with the well developed spinelike bp of Summersiella is quite unusual and different from other genera in the family Stigmaeidae. The close relationship between Summersiella and Stigmaeus is indicated by such characters as the palpgenu bearing two setae, terminal eupathidia on palptarsus basally fused and halfway separated to three long prongs, widths between n-n and m-m subequal, setae sce present, and coxa II as well as trochanter III with two setae. However, Summersiella also shares some characters with Agistemus, such as the absence of endopodal shields, the presence of a tarsal arolium (smaller in Agistemus), the minute solenidion k on genu I and the absence of k on genu II.
Adult females of Summersiella are readily distinguished by having basally angled palptarsi with the spine-like bp. Other useful characters for identifying the genus are the leg tarsal claws basally enclosed with a membranous arolium, two setae on coxa II.
Key to adult females of Summersiella
1 Central hysterosomal shield faintly sclerotized, bearing three pairs of setae; vi/vi-vi >1.0, ve/vesci > 1.3; length of solenidion w on tarsus I 26–27 µm S. coprosmae (Wood)
- Central hysterosomal shield apparently sclerotized, bearing five pairs of setae; vi/vi-vi = 0.7, ve/ ve-sci = 1.0; length of solenidion w on tarsus I 19–21 µm S. camphorae sp. nov.
Stigmaeus coprosmae Wood, 1967: 101.
Pseudostigmaeus ancydactyla, Meyer, 1969: 245
Summersiella comprosmae, Wood, 1971: 407.
Holotype female, ex leaf cavities of Coprosma australis, Riwaka River, Nelson, New Zealand, 15.i.1965, E. Collyer. Nine paratype females, same data as holotype. Deposited in the New Zealand Arthropod Collection, Landcare Research, Mt Albert, Auckland, NEW ZEALAND. Paratype females, same data as holotype.
Other material examined
One female, ex leave of Coprosma, Waitakeres Range near AK, NEW ZEALAND, 22.ii.1959, E. Collyer (labeled by R.H. Gonzalez as paratype of S. ancydactyla Gonzalez). Seven females, ex leaf cavities of Coprosma australis, Whangamoa Saddle, Nelson, NEW ZEALAND, 2.iii.1965, E. Collyer; one female, ex Coprosma australis, Manahau, north-west Nelson, NEW ZEALAND, 23.ix.1965; several females, ex Coprosma australis, Eve's Bush, NN, NEW ZEALAND, E. Collyer 3.xi.1965, 3.ix1.1968. All specimens in the New Zealand Arthropod Collection, Landcare Research, Mt Albert, Auckland, NEW ZEALAND.
Females of S. coprosmae are recognized by having the central hysterosomal shield faintly sclerotized; by having longer dorsal setae, ve exceeds base of sci; by setae ratio: vi/vi-vi > 1.0, ve/vesci > 1.3; and by the length of solenidion w on tarsus I (26–27 µm).
Gonzalez (1967) and Wood (1967) gave good descriptions of adult females. We herein provide new illustrations (Figs 1-14) giving more details, with particular reference to the chaetotaxy according to Grandjean (1944, 1946) and Kethley (1990).
Habitat and distribution
Leaves or leaf cavities (acarodomatia) on Coprosma australis in Riwaka River, Pelorus River, Manahau, and Whangamoa Saddle, NN, NEW ZEALAND (Wood 1967; this study); Palmer's Bush, Waimea Plain and Totaranui, Golden Bay, NN, NEW ZEALAND (Wood 1971).
Leaves of Metrosideros sp. in Astrolabe, Abel Tasman National Park, NN, NEW ZEALAND (Wood 1971).
Leaves of Phyllocladus trichomanoides in Chateau Tongariro, Tongariro National Park, TK, NEW ZEALAND (Wood 1971).
Coprosma australis, Eve's Bush, NN, NEW ZEALAND (this study).
Lengths of dorsal body setae, vi, sci, h1 and h2 in Gonzalez's description (1965), and vi, ve, sce, d2, e2, f1, h1 and h2 in Wood's description (1967) seem longer than those in the specimens examined (Figs. 1-12). Gonzalez (1967) miscounted the number of setae on tarsus II as 9 [it is 9+1ω; (=10)]. Wood (1967) overlooked the single seta on genu IV.
Holotype. Female, ex Cinnamomum camphora (L.), Dehua, Fujian Province, 20.xi.1996, J.Z. Lin.
Paratypes. Three females, same data as holotype.
Summersiella camphorae sp. nov. is readily distinguished from the only known species, S. coprosmae (Wood) by having an apparently sclerotized hexagonal central hysterosomal shield with five pairs of setae; by having much shorter dorsal setae (ve not reaching base of sci); by the following ratios: vi/vi-vi = 0.7, ve/ve-sci = 1.0; and by the length of solenidion ω; on tarsus I (19–21 µm).
FEMALE (n = 4)
Gnathosoma. Chelicerae conical (91–103 µm); movable digits (36–38 µm) slightly longer than one-third length of chelicerae. Palp robust (89–95 µm); tibial claw extending beyond tip of palptarsus; accessory claw slender, about half length of palpal seta bp. Seta bp well developed, about half length of tibial claw. Counts of setae, solenidia and claws on palp (from trochanter to tarsus): 0, 3, 2, 2 + 1 spinlike accessory claw + 1 claw, 3 + 1 basal claw + 1 w + 1 subterminal eupathidium + 3 basally fused eupathidia. Subcapitulum plain, without clear punctation; subcapitular setae m (25–26 µm) longer than n (20–21 µm); distance between m-m equals n-n (28–30 µm) and about twice distance between m-n (15–16 µm).
Idiosoma. Oval in shape (267–286 µm long, 173–212 µm wide). All dorsal body setae with minute barbs but not set on clear tubercles. Propodosomal setae vi (22–26 µm) no more than two thirds distance between vi-vi (34–38 µm); ve (29–34 µm) subequal distance between ve-sci (32–34 µm); sci (34–40 µm) reaching anterior edge of central hysterosomal shield. Postocular body hardly observable. Hysterosoma with a developed central shield, which bears five pairs of setae, c1 (25–26 µm), d1 (19–26 µm), d2 (29–31 µm), e1 (32–34 µm) and e2 (29–30 µm); e1 passes base of f1; ratio c1/ c1-c1 = 0.4, c1-c1/e1-e1 = 1.8 (1.7–1.8); distances between setae, c1-c1 = 69 (65–72 µm), c1-d1 = 46 (43–50 µm), d1-d1 = 89 (84–96 µm), d1-d2 = 25 (19–31 µm), d1-e1 = 35 (25–50 µm), e1-e1 = 38 (36–41 µm), e1-e2 = 30 (28–32 µm). Humeral setae c2 (20–24 µm) situated on membrane. Intercalary setae f1 (14–16 µm) on small platelets, ratio f1-f1/e1-e1 = 1.4 (1.3–1.4). Suranal shield integral, with two pairs of setae (h1 and h2), subequal in length (32–34 µm) and approximately 1.3 times length of dorsal seta (d) on femur I. Distances between setae, e1-f1 = 24 (19–28 µm), f1-f1 = 52 (49–57 µm), h1-h1 = 19 (18–19 µm), h1-h2 = 18 (16–19 µm). Ventral setae three pairs (1a, 3a and 4a), 3a (13–15 µm) slightly longer than other two pairs (11–13 µm). Three pairs of aggenital setae (ag1, ag2 and ag3) arise from individual platelets; ag3 (20–21 µm) longer than ag2 (15–17 µm) and ag1 (13–15 µm). One pair of genital setae present (g1 14–15 µm), not reaching base of ps3; three pair of pseudanal setae (ps3, ps2 and ps1) subequal in length (13–15 µm).
Legs. Length (from base of trochanter to tip of tarsus): leg I = 159 (149–169 µm), leg II = 136 (129–142 µm), leg III = 132 (130–133 µm), leg IV = 144 (137–150 µm). Setae d on femora I-IV, on genua I, II and IV all bearing minute teeth and similar to dorsal body setae. Tarsi I-IV each bearing one solenidion (ω;). Dorsal seta (d) on femur I (25–26 µm) longer than two-thirds of dorsal seta h1. Length of solenidia on tarsi, Iω; = 20 (19–21 µm), IIω; = 18 (17–20 µm), IIIω; = 4 µm, IVω; = 3 µm. Counts of setae and solenidia on legs I-IV: coxae 2, 2, 2, 2; trochanters 1, 2, 1, 1; femora 6, 4, 3, 2; genua 3 + 1κ;, 2, 0, 1; tibiae 5 + 1φ;p, 5 + 1φ;p, 5 + 1φ;p, 5 + 1φ; p; tarsi 13 + 1ω;, 9 + 1ω;, 7 + 1ω;, 7 + 1ω;.
Location of holotype
Department of Plant Protection, Fujian Agricultural and Forestry University, Fuzhou, Fujian, CHINA.
The specific name, camphorae, is from its host plant, Cinnamomum camphora.
It seems that the most important characters for distinguishing species of Summersiella are lengths of dorsal body setae and tarsal solenidia. The character of the central hysterosomal shield is only somewhat useful because it is not always clearly sclerotized in all species.
The ornamentation and arrangements of dorsal body shields are considered to be the key characters for separating genera of the Stigmaeidae. Though Summersiella camphorae sp. nov. is different from S. coprosmae (Wood) in the forms of dorsal shields, we think that it is better to place the new species in Summersiella in order to avoid erecting another monobasic genus.
The work was supported by grants to the senior author by the China Scholarship Council and the National Foundation of Natural Science of China. We thank Dr Sabina Swift (University of Hawaii, USA) and Prof Uri Gerson (Hebrew University, Israel) for the critical reviews of this manuscript. We would also like to thank Mr. J.-Z. Lin (Fujian Academy Agricultural Sciences, Fuzhou, China) for kindly providing the specimens described here as Summersiella camphorae. The senior author is also indebted to Dr. David E. Walter and to the Department of Zoology and Entomology, The University of Queensland for hosting and providing space and facility when this paper is finalized. The junior author's research on New Zealand mites was funded in part by Contract C09X0002 from the Foundation for Research, Science, and Technology, New Zealand.