Research Article |
Corresponding author: Zhi-Xiang Pan ( pzx1118@hotmail.com ) Academic editor: Louis Deharveng
© 2019 Zhi-Xiang Pan, Chen-Chong Si, Shu-Sheng Zhang.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Pan Z-X, Si C-C, Zhang S-S (2019) Close relationship between the genera Sinhomidia and Homidia (Collembola, Entomobryidae) revealed by adult and first instar characters, with description of a new Sinhomidia species. ZooKeys 872: 41-55. https://doi.org/10.3897/zookeys.872.29815
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A third species of the genus Sinhomidia is described from South China: S. uniseta sp. nov. This new species can be distinguished from the two other species of the genus by the following characters: colour pattern, single labial chaeta M, chaetotaxy on terga and ventral tube, unguis with three inner teeth, and 15 clypeal ciliated chaetae. Also, the chaetotaxy of the first instar of Sinhomidia is described for the first time in the present paper, and confirms the close relationship between Sinhomidia and Homidia. A key to species of Sinhomidia is provided.
chaetotaxy, Entomobryinae, Sinhomidia uniseta sp. nov., taxonomy
The genus Sinhomidia was defined by
The genera Sinhomidia and Homidia Börner, 1906 are closely related, the scaled Sinhomidia being recognised as sister group of unscaled Homidia (
The genus Sinhomidia is endemic to China. The type species (S. bicolor) was first recorded from Taiwan (
Specimens were sieved from leaf litter onto a tray in the field, collected by an aspirator, and stored in 99% ethanol at -20 °C. Specimens were photographed using a Nikon DS-Fi1 camera mounted onto a Nikon SMZ1000 stereomicroscope, then cleared in lactic acid, mounted in Hoyer’s medium under a coverslip, and examined under phase contrast using a Nikon 80i microscope. Lengths were measured from specimens on slide by NIS-Elements Documentation 3.1 software. Photos, illustrations and labels were enhanced by photoshop CS5 (Abode Systems).
Dorsal chaetotaxy is provided for only one side of the body. The nomenclature of cephalic chaetotaxy follows Szeptycki’s system (
Abbreviations:
Abd. abdominal segment;
Ant. antennal segment;
Gr. group;
mac macrochaeta(e);
mic microchaeta(e);
ms specialised microchaeta(e);
sens specialised ordinary chaeta(e);
Th. thoracic segment;
VT ventral tube;
(adult and subadult). Size. Body length up to 2.51 mm. Scales. Scales pointed and coarsely striated, present on dorsal side of head, thorax and abdomen (Figs
Sinhomidia uniseta sp. nov. 1–5 Habitus: 1 dorsal view of adult 2 lateral view of adult 3 ventral view of adult 4 dorsal view of subadult 5 lateral view of 1st instar larva 6 postero-median scales on Abd. IV 7 scales and bothriotrichal complex on Abd. III 8 scales on manubrium 9 dental spines.
Sinhomidia uniseta sp. nov. 10 Cephalic chaetotaxy on dorsal side 11 basis of Ant. I 12 basis of Ant. II 13 distal part of Ant. II 14 Ant. III organ 15 distal part of Ant. IV 16 labrum 17 clypeal chaetotaxy 18 labium 19 labial palp 20 maxillary outer lobe 10–16 dorsal view 17–19 ventral view 20 lateral view. Scale bars: 50 μm.
Sinhomidia uniseta sp. nov. 25 Dorsal chaetotaxy of Abd. I–Abd. V tergites 26 anterior face of ventral tube 27 lateral flap of ventral tube 28 posterior face of ventral tube 29 tenaculum 30 manubrial plaque 31 basal part of dens 32 distal part of dens and mucro 25, 26, 31, 32 dorsal view 28–30 ventral view 27 lateral view. Scale bars: 50 μm.
Size.
Body length up to 0.79 mm. Colour pattern. Ground colour whitish, eye patches dark, antennae and femurs of hind legs with weak pigments, posterior half of Abd. II and whole Abd. III pigmented. The colour pattern is similar to that of adults, but paler overall (Fig.
The first instar larvae of Sinhomidia uniseta sp. nov. 33 Dorsal cephalic chaetotaxy 34 chaetotaxy of Th. II–Abd. III tergites 35 chaetotaxy of Abd. IV–VI tergites 36 chaetotaxy of Ant. I–III 37 distal part of Ant. IV 38 labium 39 ventral tube 40 manubrium 41 dens 42 tenaculum 33–37, 39–42 dorsal view 38 ventral view. Scale bars: 50 μm.
Found in leaf litter of Calamus thysanolepis.
1♀ on slide, China, Guangdong Province, Guangzhou city, Tianhe District, Longdong reservoir, 23°14.134'N, 113°23.94'E, altitude 127±5 m, sample number 4661, collected by Z-X PAN and S-S ZHANG, 24-III-2018. Paratypes. 4♀1♂adults, 1 subadult and 1 first instar larva on slides and 3 adults in ethanol, same data as holotype. All types were deposited at the School of Life Sciences, Taizhou University.
Specific epithet refers to the single chaeta M on labial basis (uni + seta).
Sinhomidia uniseta sp. nov. can be easily distinguished from the other two species of the genus by the dark pigment present on the lateral and anterior margins of Th. II, posterior margin of Abd. II and whole Abd. III, labial single M chaeta, three mac and ms external to sens on dorsal side of Abd. I, 5 (7) mac in postero-median area of Abd. IV, middle sens posterior to m3 on Abd. V, and three teeth on inner side of unguis. Detailed differences between the three species of Sinhomidia are listed in Table
Characters | S. uniseta sp. nov. | S. bicolor | S. guangxiensis |
---|---|---|---|
Colour pattern | |||
Lateral stripes on head | absent | present | absent |
Pigment on Th. II | along lateral and anterior margins, rarely whole | along lateral and anterior margins | whole |
Pigment on Abd. I | posterior margin | whole | whole |
Middle dark band dorsally on Abd. IV | absent | present | present |
Posterior dark band dorsally on Abd. IV | discontinuous | continuous | continuous |
Scales on antennae, legs and manubrium | present | present | absent |
Maximum body length (mm) | 2.5 | 3.4 | 2.4 |
Chaetotaxy | |||
Chaeta M on labrum | undoubled | doubled | doubled |
Chaetae a2 and a5 on Abd. I | absent | absent | present |
Chaeta a3 on Abd. II | mic | mic | mac |
Postero-medial mac on Abd. IV | 5 (7) | 9 | 8 |
Inner teeth of unguis | 3 | 4 | 4 |
Smooth/ciliated chaetae on each lateral flap of ventral tube | 5–9/10–11 | 14/14 | 3/13 |
The genus Sinhomidia was named referring to many features shared with Homidia (
These two genera differ nevertheless by several characters, such as scales (present in Sinhomidia versus absent in Homidia) (Figs
Comparison of the first instar larvae among nine species of Entomobryidae.
Tergite | Chaetae | S. un | H. q | H. j | S. um | S. b | O. f | H. n | E. m | P. a |
---|---|---|---|---|---|---|---|---|---|---|
Th. II | m1 | mac | mac | mac | mac | mac | mac | mic | mac | mac |
m2 | mic | mic | mic | mic | mic | mic | mic | mic | scale | |
p4 | mic | mic | mic | mic | mic | mic | mic | mic | mic | |
p5 | mic | mac | mac | mic | mac | mac | mic | mic | mac | |
P6 | mic | mic | mic | mic | mic | mic | mic | mic | mic | |
Th. III | a1 | mac | mac | mic | mic | mac | mac | mic | mic | mic |
a2 | mac | mac | mac | mac | mac | mac | mic | mic | mic | |
a3 | mac | mac | mac | mac | mac | mic | mic | mic | mic | |
a4 | mac | mac | mac | mac | mac | mac | mic | mic | – | |
a5 | mac | mac | mac | mac | mac | mac | mac | mac | mac | |
m1 | mic | mic | mic | mic | – | mic | mic | – | – | |
m2 | – | – | – | – | mac | – | – | mic | mac | |
m5 | mac | mac | mic | mic | mic | mic | mic | mic | mic | |
p1 | mac | mac | mac | mac | mac | mac | mac | mic | mac | |
p2 | mac | mac | mac | mac | mac | mac | mac | mic | mac | |
Abd. I | a4 | – | – | – | – | – | – | – | mic | – |
a5 | mic | mic | mic | mic | mic | mic | mic | – | mic | |
m2 | mac | mac | mac | mic | mac | mac | mac | mic | mac | |
m4 | mac | mac | mac | mac | mac | mac | mic | mac | mac | |
m6 | mic | mic | mic | mic | mic | mic | mic | mic | mic | |
Abd. II | a1 | mic | mic | mic | mic | mic | mic | mic | mic | mic |
a2 | mic | mic | mic | mic | mac | mac | mic | mic | mac | |
a6 | mic | mic | mic | mic | mic | mic | mic | – | mic | |
a7 | mic | mic | mic | mic | mic | mic | mic | mic | – | |
m3 | mac | mac | mac | mac | mac | mac | mac | mac | mac | |
m4 | mic | mic | mic | mic | mic | – | – | mic | mic | |
m5 | mac | mac | mac | mac | mac | mac | mic | mic | mac | |
m6 | mic | mic | mic | mic | mic | mic | mic | mac | mic | |
m7 | mic | mic | mic | mic | – | mic | mic | – | mic | |
p4 | mic | mic | mic | mic | mic | mic | mic | – | – | |
p5 | mic | mic | mic | mic | mic | mic | – | – | – | |
Abd. III | a1 | mic | mic | mic | mic | mic | mic | mic | mic | mic |
a2 | mic | mic | mic | mic | mic | mic | mic | mic | mic | |
a7 | mic | mic | mic | mic | mic | mic | mic | – | mic | |
m4 | mic | mic | mic | mic | mic | – | mic | – | mic | |
am6 | mac | mac | mic | mic | mic | mac | mac | mac | mac | |
pm6 | mac | mac | mac | mic | mac | mac | mac | mac | mac | |
p4 | mic | mic | mic | mic | – | mic | mic | mic | – | |
p5 | mic | mic | mic | mic | mic | mic | – | mic | – | |
Abd. IV | A4 | mac | mic | mic | – | – | – | – | mic | – |
A5 | – | mic | – | mic | mic | – | – | – | mic | |
A6 | mac | mic | mac | mic | mic | – | mic | ? | mic | |
B4 | mac | mac | mic | mac | mic | – | – | mic | mic | |
B5 | mac | mac | mac | mac | mac | mic | mic | mac | mac | |
B6 | mac | mic | mic | mic | mic | mic | – | mic | mic | |
E2 | mac | mac | – | – | mic | mac | mic | – | mic | |
E3 | mac | mac | mac | mac | mac | – | – | mac | mic | |
Abd. V | a1 | mic | mic | mic | mic | mic | mic | mic | mic | mic |
a3 | mic | mic | mic | mic | mic | – | – | – | – | |
m2 | mac | mac | mac | mac | mac | mac | mac | mic | mac | |
m3 | mac | mac | mac | mic | mac | mac | mac | mic | mac | |
a5 | mic | mic | mic | mic | mic | mac | mac | – | – | |
m5 | mac | mac | mac | mic | mac | – | mic | – | mac | |
a6 | mic | mic | mic | mic | mic | mic | mic | – | mic | |
p1 | mic | mic | mic | mic | mic | mic | mic | mic | mic | |
p2 | – | – | – | – | – | – | – | mic | – | |
p3 | mic | mic | mic | mic | mic | mic | mic | – | mic | |
p4 | mic | mic | mic | mic | mic | mic | – | mic | mic | |
p5 | mic | mic | mic | mic | mic | mic | – | – | – | |
ap6 | mic | mic | mic | mic | mic | mic | mac | mic | mic |
Scales are intuitively considered to have evolved from ordinary chaetae, present in many species, and are important diagnostic characters for classification at the subfamilial and tribal levels of the family Entomobryidae. The tribe Willowsiini is well defined by the absence of dental scales (
1 | Abd. I entirely dark pigmented, Abd. IV with a middle dark band, claw with 4 inner teeth, labial chaeta M doubled | 2 |
– | Abd. I with posterior margin dark pigmented, Abd. IV without middle dark band, claw with 3 inner teeth, labial chaeta M undoubled | S. uniseta sp. nov. |
2 | Head with lateral dark stripes, chaetae a2 and a5 absent on Abd. I | S. bicolor |
– | Head without lateral dark stripes, chaetae a2 and a5 present on Abd. I | S. guangxiensis |
This study was supported by the National Natural Science Foundation of China (36101880) and Zhejiang Provincial Natural Science Foundation of China (LY15C040001). Also, thanks given to Professor Shidi SHI who provided comments on this manuscript.