Research Article |
Corresponding author: Feng Zhang ( xtmtd.zf@gmail.com ) Academic editor: Louis Deharveng
© 2018 Yuanhao Ren, Zhaohui Li, Feng 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:
Ren Y, Li Z, Zhang F (2018) A new species of Dicranocentrus Schött from Hainan (China) with a key to the Chinese species of the genus (Collembola, Entomobryidae). ZooKeys 762: 59-68. https://doi.org/10.3897/zookeys.762.23926
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A new species, Dicranocentrus hainanicus Ren & Zhang, sp. n., is described from Hainan Province, China. Complete tergal chaetotaxy including microchaetae is illustrated and discussed. It is characterized by having the dental spines arranged in 2–3 rows, two inner teeth on unguis, 5, 2, 2 central macrochaetae on Abd. I–III, two inner S-chaetae on Abd. V displaced anteriorly, and the additional microchaetae associated with the S-chaeta acc.p6 on Th. II–Abd. II. It is most similar to D. chenae Ma, Chen & Soto-Adames but differs from the latter in the number and arrangement of dental spines and the absence of macrochaeta Pa1 on dorsal head. A key to the Chinese species of the genus is provided.
chaetotaxy, Dicranocentrus hainanicus sp. n., Heteromurinae
The genus Dicranocentrus Schött, 1893 is widespread in pantropical regions. It is characterized by having the first and the second antennal segments subdivided, the third and the fourth antennal segments annulated, eyes 8+8, prelabral chaetae not bifurcated, postantennal organ absent, dental lobe without compound spines, dental spines present or absent, and the mucro bidentate with a basal spine (
Specimens were cleared in Nesbitt’s fluid, mounted under a coverslip in Hoyer’s solution, and studied using a ZEISS AXIO Scope.A1 microscope and Axiocam camera. Dorsal body chaetae nomenclature follows
Th. thoracic segment;
Abd. abdominal segment;
Ant. antennal segment;
mac macrochaeta/ae;
mes mesochaeta/ae;
mic microchaeta/ae;
ms S-microchaeta/ae;
sens ordinary tergal S-chaeta/ae.
Holotype: ♂ on slide, China, Hainan Province, Wuzhi Mountain, 18.903°N, 109.688°E, altitude ca. 901 m, 29 Dec 2015, DY Yu leg. (#15HN5). Paratypes: four ♀♀ on slides and three juveniles and one adult in alcohol, same data as holotype. All deposited in NJAU.
Named after the type locality where the new species was collected.
No obvious color pattern. Mac S2 present and mac Pa1 absent on dorsal head. Labial chaetae l1 and l2 smooth. Inner tibiotarsi and manubrium dorsally with smooth chaetae. Unguis with two inner teeth and without unpaired tooth. Tenent hairs acuminate. Den with 30–41 inner spines arranged in 2–3 rows. Th. II with two medio-medial, two medio-sublateral and eight posterior mac, and mac p5 present. Abd. I–IV with 5, 2, 2, 5 central mac. An additional mic associated with acc.p6 present on Th. II–Abd. II. Tergal sens as 2, 2|1, 3, 3, (3+≈35), 4; on Abd. V two inner sens anterior to lateral two.
Body length (head + thorax + abdomen) up to 3.96 mm. Ground color yellow. Antennae gradually dark purple towards tip. Eye patches dark (Fig.
Antenna approx. 3.5 times as long as cephalic diagonal. Antennal segment ratio as Ia: Ib: IIa: IIb: III: IV= 1: 4.04–5.29: 1.19–1.57: 4.57–6.29: 13.04–18.08: 4.71; ratio in holotype as 1: 4.04: 1.26: 4.57: 13.04 (Ant. IV lost). Ant. III distally and IV annulated and often fused. Smooth spiny mic at base of antennae indistinctly separated from ordinary mic and thus their number unclear (Fig.
Eyes 8+8. Labral papillae four, all with a pointed tip and outer two slightly larger. Prelabral and labral chaetae 4/5, 5, 4, all smooth. Clypeal chaetae ciliate on prefrontal and frontal areas but their number unclear; lateral L1 and L2 smooth. Dorsal cephalic chaetotaxy with 13–16 antennal (An), four anterior (A), three median (M), eight sutural (S), one postocular (Po=Pa5) mac, and seven (Pa2–3, Pm3, Pp3, Pp5, Pe3–4) posterior (P) mac; mac Pa1 absent; inter-ocular chaetae as p, s, t (Fig.
Dicranocentrus hainanicus sp. n. 15Ant. I organ 16 left Ant. III organ 17 dorsal cephalic chaetotaxy 18 maxillary outer lobe (right side) 19 lateral process of labial palp (left side) 20 labial triangle (right side) 21 postlabial chaetae along groove 22 trochanteral organ 23 hind claw (posterior side) 24 anterior face of ventral tube 25 manubrial plaque (right side), arrow indicating that it is often absent 26 distal part of manubrium ventrally.
Trochanteral organ with 29–44 smooth spine-like chaetae; 12–13 in L-shaped arms and 17–31 between arms (Fig.
Th. II with two (m1, m2) medio-medial, two (m4, m4i) medio-sublateral and eight (p1, p1i, p1p, p2, p2a, p2p, p2e, p3, p5) posterior mac; m4p, m5, p1a, p4, p6 as mic. Th. III with 15 (a1–6, a4i, a6i, m6, p1–3, p1i, p2a, m6p) mac; a7 and m7 as mes; m1, m4–5 and p4–6 as mic. Abd. I with five (a2–3, m2–4) mac; a1, a5–6, m5–6, p5–6 as mic. Abd. II with two (m3, m3e) mac; a2–3, a5–6, m4–7 and p4–7 as mic (Fig.
In litter of coniferous and broad-leaved mixed forests.
As a member of sundanensis-group (cephalic mac S2 present), D. hainanicus sp. n. is similar to Dicranocentrus chenae Ma, Chen & Soto-Adames in most features including two inner teeth on unguis and tergal macrochaetae, but differs from it in the absence of mac Pa1 on dorsal head, mac p5 present on Th. II and the abundant (30–41) dental spines arranged in 2–3 rows (single row in D. chenae). The absence of outer tooth on unguis is also interesting but the detail is often lacking or overlooked in descriptions of known species.
Nearly complete dorsal chaetotaxy is again illustrated and compared with
1 |
Abd. I with 5+5 mac (Fig. |
2 |
– | Abd. I with 3+3 mac | 3 |
2 | Mac Pa1 present on dorsal head; Th. II without p5 mac; dens with 15–19 inner spines arranged in a row | chenae Ma, Chen & Soto-Adames, 2006 |
– | Mac Pa1 absent on dorsal head (Fig. |
hainanicus sp. n. |
3 | Abd. III with 1+1 central mac | liuae Xu & Zhang, 2014 |
– |
Abd. III with 2+2 central mac (Fig. |
4 |
4 | Abd. II with 3+3 mac; Abd. III with 3+3 lateral mac | indicus Bonet, 1930 |
– |
Abd. II with 2+2 mac (Fig. |
wangi Ma & Chen, 2007 |
This study was supported by the National Natural Science Foundation of China (31772491) and the Fundamental Research Funds for the Central Universities (KYX201617) granted to Feng Zhang and the Key Subject of Ecology of Jiangsu Province granted to Yuanhao Ren and Zhaohui Li. Thanks to Mr. Morgan A. McClure, who checked the English text.