Research Article |
Corresponding author: Wei-Chun Li ( weichunlee@126.com ) Academic editor: Martin Schwentner
© 2024 Jin Wang, Chong-Hui Yao, Chao Jiang, Wei-Chun Li.
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The genus Lucasioides Kwon, 1993 (Isopoda: Oniscidea: Agnaridae) occurs in Asia, but confined only to China, Japan, Korea, and Russian Siberia. The ambiguously morphological differences among some members of the genus make a dilemma: the species recognition, whether morphologically similar or different, is uncertain. In this paper, we present first morphometric and molecular data for the genus from a broad sample. DNA sequences (mitochondrial COI, nuclear 18S rRNA, 28S rRNA, and NaK) were generated and integrated with morphological evidence to reveal the cryptic species and delimit the new species within the genus. Seven species are described as new to science: Lucasioides digitatus sp. nov., L. dissectus sp. nov., L. dianensis sp. nov., L. formosus sp. nov., L. gracilentus sp. nov., L. schmidti sp. nov. and L. subcurvatus sp. nov. To date, Lucasioides species from China are 44.4% as many as all the known congeners worldwide, showing the exceptional species diversity of Lucasioides species from China. The results demonstrate that the integrative taxonomy is especially important to reveal the cryptic species among the high morphological similarity of taxa, as well as providing an effective way for species identification to accelerate the exploration of woodlice biodiversity.
DNA barcode, geometric morphometrics, morphology, new species, Oniscidea, species delimitation
The terrestrial isopods (common name: woodlice) or Oniscidea represent a suborder within the Isopoda. More than 4,000 species in more than 500 genera and 38 families are known worldwide so far (
Lucasioides Kwon, 1993 is a genus of the family Agnaridae Schmidt, 2003, occurs in Oriental and Palaearctic Regions, with its distribution restricted to China, Japan, Korea and Russian Siberia (
In the past, Lucasioides was proposed as a subgenus of Protrаcheoniscus by
To understand the woodlice distribution, annual mean temperature has been proposed to an important limiting factor (
At present, the ambiguous differences among some members of the genus are difficult to be verified to interspecific divergence or intraspecific variation based only in traditional morphological. Moreover, the molecular studies of the genus are scarce. In this paper, we present the first molecular data for the genus from a broad sample. DNA sequences were generated and integrated with morphological evidence to explore an effective way for species identification.
The specimens for this study were collected by tweezers, fixed in 100% ethanol, stored in the
Insect Museum, Jiangxi Agricultural University, Nanchang, China (
The whole body of the specimens was placed in acid-fuchsin staining buffer for twelve hours. The appendages were dissected and mounted on micro preparations in a neutral balsam mounting medium using a Zeiss Stereo Discovery V12 microscope. The morphological terminology followed
Images were taken with a camera Zeiss AxioCam Icc 5 attached to a Zeiss Stereo Discovery V12 microscope. The line drawings were drawn by the GNU Image Manipulation Program (
For morphometric analysis, a total of 252 habitus in the dorsal view of Lucasioides species were selected. The images were converted into TPS file by tpsUtil 1.56 (Rohlf 2013). To evaluate variation in body shape, fourteen landmarks were placed on the posterior angle of each pereonite and two landmarks on the anterior protruding angle of the first pereonite. Landmarks for all images were aligned by performing Procrustes Fit, and the landmarks were recorded using TPSdig 2.17 (Rohlf 2013). To visualize shape variations across morphospace, principal component analyses (PCAs) and canonical variate analyses (CVAs) were conducted by MorphoJ (
Genomic DNA was extracted from muscles of samples by the TaKaRa MiniBEST Universal Genomic DNA Extraction Kit. Partial of cytochrome c oxidase subunit I (COI), and partial of 18S and 28S rRNA genes, along with a fragment of the nuclear protein-coding gene sodium-potassium ATPase α-subunit (NaK) were amplified using polymerase chain reaction (PCR). Fragment of COI gene were amplified using the primers LCO1490/HCO2198 (
The resulting forward and reverse sequences of Lucasioides members (Table S1) were assembled by SeqMan, manually checked for errors, and searched with Blast to expose contaminants. The sequences of protein-coding genes COI and NaK were aligned by MACSE (
We conducted Bayesian inference (BI) and Maximum likelihood (ML) analyses by four concatenated genes (COI, 18S, 28S and NaK). The BI analyses were conducted in MrBayes 3.2.6 (Ronquist et al. 2012) on the platform of PhyloSuite (
Furthermore, pairwise p-distances of all the sequences of COI, 18S, and 28S sequences were calculated by MEGA X (
In molecular species delimitations, COI was employed to generate initial species hypotheses. Automatic barcode gap discovery (ABGD) automatically clustered sequences into candidate species using online version with the relative gap width was set to one (
Finally, we analysed the multilocus data (COI, 18S, 28S and NaK) under the multispecies coalescent model to delimit species with BPP 4.4 (
The cartographic illustration was made using DIVA-GIS 7.5 (
The morphological characters of the specimens collected from China were analysed using external traits and dissected appendages. As a result, seven members were preliminarily recognized, including four known ones [L. gigliotosi (Arcangeli, 1927), L. isseli (Arcangeli, 1927), L. pedimaculatus Kwon & Taiti, 1993 and L. nudus Li, 2017], and three new species. Among them, the specimens identified as L. isseli (Arcangeli, 1927) include four kinds of phenotypes, and the specimens were recognized as L. nudus Li, 2017 have another phenotype as well. It is difficult to verify their minor differences are due to interspecific divergence or intraspecific variation, nor reveal the cryptic species based on traditional morphology.
In the results of geometric morphometrics, a total of twenty-eight principal components were obtained in the principal component analyses (PCA). The first principal component (PC1) takes up 55.15% of the total shape variation, and PC1 versus PC2 showed an overlapping distribution of species in morphospace (Fig.
In PCR amplification, a total of 248 sequences from 66 specimens were retrieved successfully, including a mitochondrial COI gene and three nuclear genes (18S, 28S and NaK) (Table S1). We analysed the phylogenetic relationships based on the four-gene data (COI, 18S, 28S and NaK). Both Maximum likelihood (ML) and Bayesian (BI) analyses revealed eleven main clades within the genus Lucasioides [Fig.
Furthermore, we calculated the pairwise p-distances based on the eleven-species hypothesis using COI, 18S, and 28S data of the Lucasioides samples. In the results of COI and 28S, the maximum intraspecific distances (COI: 0−6.54%; 28S: 0−5.34%) are much smaller than the minimum interspecific distances (COI: 10.20−21.00%; 28S: 7.82−23.70%) (Tables S2, S4), supporting the eleven-species hypothesis and the partial COI and 28S sequences can be applied as a useful DNA barcode marker. Meanwhile, the results of 18S also show the maximum intraspecific distances (0−4.38%) are smaller than the minimum interspecific distances (5.94−19.37%) except for L. subcurvatus sp. nov. and L. dissectus sp. nov. (Table S3). The interspecific distances between them are 4.34−13.49%, which might cause by the inconsistent lengths of the sequences between L. subcurvatus (825−1028 bp) and L. dissectus (1808−1824 bp).
In molecular species delimitation, clade boundaries provided clear limits among morphospecies. As shown in Fig.
Finally, we treated the eleven groups within Lucasioides as valid species by integrating the results of morphological taxonomy, geometric morphometrics, phylogenetic analyses and molecular species delimitation. Seven species are described as new to science. To date, Lucasioides species from China are 44.4% as many as all the known congeners. The subsequently described and further remarks of the new species are given in the taxonomic section.
Family Agnaridae Schmidt, 2003
Protracheoniscus (Lucasioides) Arcangeli, 1952: 298, nomen nudum.
Lucasioides Vandel, 1969: 159, nomen nudum.
Lucasioides Kwon, 1993: 143.
Porcellio (Lucasius) gigliotosi Arcangeli, 1927.
Body flat, dorsally granulated, gland pores absent. Cephalon with frontal line separated from vertex by groove, median and lateral lobes well-developed. Epimeron of first pereonite with sinuous or rounded posterior margin. Noduli laterales on pereonites 1 and 5−7 closer from lateral margins, and 2−4 shifted from lateral margins. Pereopods 1−4 with brush of long setae on sternal margins of merus and carpus. Pleopodal exopods 1−5 with Protracheoniscus-type pseudotrachea (
Holotype. CHINA • ♂; Jiangxi Province, Jiujiang City, Nanshan National Forest Park; 29.2514°N, 116.2071°E; el. 79 m a.s.l.; 17.viii.2022; W.C. Li leg. (DNA nos. NS2201, Prep. slide no. L22090). — Paratypes. • 3 ♂♂, 2 ♀♀; same data as the holotype (DNA nos. NS2002−NS2004); CHINA • 3 ♂♂, 5 ♀♀; Jiangxi Province, Pingxiang City, Nankeng Forest Farm; 27.4650°N, 113.8940°E, el. 590 m a.s.l.; 21.vi.2011; W.C. Li leg. (DNA nos. NKLC2001−NKLC2008, Prep. slide nos. L17321−L17326).
Pereonite 1 with acute postero-lateral corner; pleopod 1 exopod with bilobed apex, and outer lobe approximate three times as long as inner lobe.
Body length of males 7.0−8.5 mm, of females 7.5−9.5 mm. Color in alcohol brown, dorsum granulated, bearing irregular white muscle spots (Fig.
Habitus of male Lucasioides species in dorsal view. A L. dissectus sp. nov.; B L. isseli (Arcangeli, 1927); C L. dianensis sp. nov.; D L. digitatus sp. nov.; E L. schmidti sp. nov.; F L. nudus Li, 2017; G L. formosus sp. nov.; H L. gracilentus sp. nov.; I L. subcurvatus sp. nov. (Scale: 1 mm).
Latin “dissectus” = partite. The new species name refers to the male pleopod 1 exopod conspicuously bilobed at apical apex.
The new species is very similar to L. isseli (Arcangeli, 1927) in having the apical tip of pleopod 1 exopod conspicuously bilobed, and the outer lobe much longer than the inner lobe. But it can be distinguished by the shape of median lobe of the cephalon angled in anterior middle margin, and pereonite 1 with an acute postero-lateral corner (Fig.
Holotype. CHINA•1♂; Yunnan Province, Yuxi City, Tonghai County, Xiushan Historical and Cultural Park; 24.0978°N, 102.7446°E, el. 1989 m a.s.l; 2.viii.2022; J. Wang, X.K. Hong leg. (DNA nos. XS2201, Prep. slide no. L22077). — Paratypes. • 2♂♂, 3♀♀; same data as the holotype (DNA nos. XS2202−XS2206). CHINA • 2♂♂; Yunnan Province, Kunming City, Xishan Park, Taihuasi; 26.9615°N, 102.6303°E; el. 2149 m a.s.l.; 2.viii.2021; J. Wang, X.G. Zeng, Z.L. Wan leg. (DNA nos. THS2101, THS2105, Prep. slide no. L21053).
Pleopod 1 exopod with bilobed apex, and outer lobe twice as long as inner lobe, each lobe with one single spine.
Body length of males 6.0−9.8 mm, of females 7.0−9.5 mm. Color in alcohol blackish brown, dorsum granulated, bearing irregular white muscle spots (Fig.
The new species is named after its type locality Yunnan Province, and “dian” is the shortened form of this province of China.
The new species is very similar to L. isseli (Arcangeli, 1927) in overall appearance and male pleopods, but it can be distinguished in having two setae at the distal apex of the male pleopod 1 exopod. Furthermore, the molecular data recognized both species as distinct taxonomic entities they can also be separated based on molecular analyses (Fig.
Holotype. CHINA • 1 ♂; Jiangxi Province, Yichun City, Jingan County, Sanzhualun; 29.0490°N, 115.2611°E, el. 220 m a.s.l.; 19.vii.2012; W.C. Li leg. (DNA no. SZL2002, Prep. slide nos. L17309−L17314). — Paratypes. • 3♀♀; same data as the holotype (DNA nos. SZL2001, SZL2003 and SZL2004).
Cephalon with arched median lobe; pereonite 1 with blunted postero-lateral corner; pleopod 1 exopod with finger-like outer lobe, inner lobe inconspicuous.
Body length of males 6.2 mm, of females 6.3−8.0 mm. Color in alcohol blackish brown or yellowish brown, dorsum granulated, bearing irregular white muscle spots (Fig.
Latin “digitatus” = finger-like. The new species name refers to the male pleopod 1 exopod with a finger-like lobe on outer side.
The new species is very similar to L. isseli (Arcangeli, 1927) in having the cephalon with an arched median lobe, and the first pereonite with a blunted postero-lateral corner. But it can be distinguished in having the pleopod 1 exopod with an undeveloped inner lobe (Fig.
Holotype. CHINA • 1 ♂; Hunan Province, Huaihua City, Xupu County, Lingcui Mountain Park; 27.9074°N, 110.5778°E, el. 214 m a.s.l.; 15.viii.2019; W.C. Li, J.B. Yang leg. (DNA no. LCS2020, Prep. slide nos. L2046−L2048). — Paratypes. • 2 ♀♀; same data as the holotype (DNA no. LCS2008). CHINA • 1 ♂, Hunan Province, Loudi City, Xinhua County, Shizi Mountain Park; 27.7311°N, 110.3338°E, el. 235 m a.s.l.; 16.vii.2019; W.C. Li, J.B. Yang leg. (DNA no. SZS1901, Prep. slide nos. L19034−L19036).
Pereonite 1 slightly sinuous on posterior margin of epimeron, postero-lateral corner nearly right-angled; pleopods 1, 3−5 exopods out curved on outer margins; pleopod 1 exopod with outer lobe much longer than inner lobe.
Body length of males 4.6−6.9 mm, of females 5.51 mm. Color in alcohol blackish brown, dorsum slightly granulated, bearing irregular white muscle spots. Pereonite 1 slightly sinuous on posterior margin of epimeron, postero-lateral corner nearly right-angled (Fig.
The new species is named after Dr. Christian Schmidt (Senckenberg Naturhistorische Sammlungen Dresden, Germany), who contributed profoundly to systematic research in woodlice; noun (name) in the genitive case.
The new species is very similar to L. nudus Li, 2017 in having the outer lobe of the pleopod 1 exopod much longer than the inner lobe. But it can be distinguished by the slenderer body shape and less developed epimeron (Fig.
Holotype. CHINA • 1♂; Yunnan Province, Lijiang City, Yulong County, Liming Lisu Ethnic Township, Houka; 27.1469°N, 99.8193°E, el. 1921 m a.s.l.; 8.vii.2022; J. Wang, X.K. Hong leg. (DNA no. HK2201, Prep. slide no. L22081). — Paratypes. • 2 ♂♂, 2 ♀♀; same data as the holotype (DNA nos. HK2202−HK2205). CHINA • 1 ♂, 4 ♀♀; Yunnan Province, Lijiang City, Zimei lake; 26.9891°N, 100.1966°E, el. 2724 m a.s.l.; 7.vii.2022; J. Wang, X.K. Hong leg. (DNA nos. ZMH2201−ZMH2205, Prep. slide no. L22082). • 2 ♂♂, 4 ♀♀; Yunnan Province, Dali City, Jianchuan County, Qianshi Mountain; 26.5328°N, 99.8877°E, el. 2364 m a.s.l.; 11.vii.2022; J. Wang, X.K. Hong leg. (DNA nos. QSS2201−QSS2206, Prep. slide no. L22076). • 4♀♀; Yunnan Province, Lijiang City, Gucheng District; 26.9258°N, 100.2079°E, el. 2465 m a.s.l.; 7.vii. 2022; J. Wang, X.K. Hong leg. (DNA nos. LJGC2201−LJGC2204). • 3♀♀; Yunnan Province, Lijiang City, Meiquan Village; 26.9058°N, 100.1499°E, el. 2486 m a.s.l.; 6.vii.2022; J. Wang, X.K. Hong leg. (DNA nos. MQC2201−MQC22032205).
Pereonite 1 slightly sinuous on posterior margin of epimeron, postero-lateral corner nearly right-angled; noduli laterales on pereonites 1−4 shifted from lateral margins than those of pereonites 5−7; pereopod 7 remarkably expanded on dorsal margin of carpus; pleopod 1 exopod slightly concave at posterior tip.
Body length of males 6.3−8.0 mm, of females 5.5−11.0 mm. Color in alcohol blackish brown, dorsum granulated, bearing irregular yellowish white muscle spots (living individuals with yellowish blue muscle spots). Pereonite 1 slightly sinuous on posterior margin of epimeron, postero-lateral corner nearly right-angled (Fig.
Latin “formosus” = beautiful. The new species name is an allusion to beautiful yellowish blue muscle spots on the dorsum of the living individuals.
The new species is not strictly consistent with the generic characters of Lucasioides because of the noduli laterales on pereonites 1−4 shifted from lateral margins than those of pereonites 5−7 instead of the noduli laterales on pereonites 2−4 much farther from lateral margins than those of pereonites 1, 5−7. It is difficult to give a ready answer for this dilemma based on the morphological evidence alone. In the phylogenetic analyses, the relationship between this species and the other Lucasioides species is well-supported (Fig.
Holotype. CHINA • 1 ♂; Fujian Province, Putian City, Hugong Mountain; 25.3490°N, 119.0077°E, el. 462 m a.s.l.; 4.vii.2021; X.G. Zeng, J. Wang leg. (DNA no. HGS2104, Prep. slide no. L21060). — Paratypes. • 5 ♂♂, 3 ♀♀, same data as the holotype (DNA nos. HGS2105−HGS2112).
Pereonite 1 nearly straight on posterior margin of epimeron, postero-lateral corner convex; pleopod 1 exopod concave at posterior apex and formed two broad lobes, inner lobe longer and broader than outer lobe.
Body length of males 4.8−5.0 mm, of females 6.0−8.0 mm. Color in alcohol blackish brown, dorsum granulated, bearing irregular white muscle spots (Fig.
Latin “gracilentus” = slender. The new species name refers to the slender habitus of the specimens.
The new species is also inconsistent within Lucasioides if we recognized it by using the morphological traits alone. However, all the mounted structures of this species support it to be assigned as Lucasioides member. Furthermore, the phylogenetic relationship between this species and the other Lucasioides species is well-supported (Fig.
The new species is similar to L. boninshimensis (Nunomura, 1987) in having the convex postero-lateral corner of pereonite 1. But it can be distinguished by the pleopod 1 exopod with inner lobe broader than outer lobe, endopod with a beak-shaped posterior tip (Fig.
Holotype. CHINA • 1 ♂; Sichuan Province, Leshan City, Mabian Yi Autonomous County, Minjian Town, Zhang Youfang Village; 28.8439°N, 103.5475°E, el. 600 m a.s.l.; 12.viii. 2012; W.C. Li leg. (DNA no. DFD2006, Prep. slide nos. L2073−L2075). — Paratypes. • 1 ♂, 3 ♀♀; same data as the holotype (DNA nos. DFD2003b, DFD2003−DFD2005). CHINA • 1 ♂, Guizhou Province, Bijie City, Qianxi County, Qianxi Railway Station; 26.9937°N, 106.0413°E, el. 1221 m a.s.l.; 4.viii. 2020; X.G. Zeng, J.B. Yang leg. (DNA no. GQX2204, Prep. slide no. L22098).
Pereonite 1 with right-angled postero-lateral corner; pleopod 1 exopod slightly concave, forming two inconspicuous lobes.
Body length of males 6.1−6.9 mm, of females 5.2−6.0 mm. Color in alcohol blackish brown, dorsum slightly granulated, and with irregular white muscle spots (Fig.
Latin “subcurvatus” = subcurved. The new species name refers to the shape of pleopod 1 exopod with a subcurved apex.
The new species is very similar to L. formosus sp. nov. in having the pleopod 1 exopod slightly concave and forming two inconspicuous lobes. But it is easy to be distinguished in having the noduli laterales on pereonites 2−4 shifted from lateral margins than the noduli laterales on pereonites 1, 5−7 (Fig.
1 | Pereonite 1 concave near lateral side of posterior margin | 2 |
1’ | Pereonite 1 not concave near lateral side of posterior margin | 32 |
2 | Pereonite 1 slightly concave near lateral side of posterior margin | 3 |
2’ | Pereonite 1 obviously sinuate near lateral side of posterior margin | 14 |
3 | Male pleopod 1 exopod not concave at distal apex | 4 |
3’ | Male pleopod 1 exopod concave at distal apex | 7 |
4 | Male pleopod 1 exopod half-moon-shaped | 5 |
4’ | PMale pleopod 1 exopod triangular or bean-shaped | 6 |
5 | Male pleopod 2 exopod conspicuously concave near middle of outer margin ( |
L. nakadoriensis (Nunomura, 1991) |
5’ | Male pleopod 2 exopod nearly straight in middle of outer margin ( |
L. nishimurai (Nunomura, 1987) |
6 | Male pleopods 1−2 exopods triangular ( |
L. daliensis Nunomura & Xie, 2000 |
6’ | Male pleopod 1 exopod bean-shaped, male pleopod 2 exopod broad at basal part, distal two thirds thin and long ( |
L. longicaudatus Nunomura & Xie, 2000 |
7 | Male pleopod 1 exopod with inner lobe as long as outer lobe | 8 |
7’ | Male pleopod 1 exopod with inner lobe not as long as outer lobe | 10 |
8 | Noduli laterales on pereonite 7 much farther from lateral margins ( |
L. cavernicolus Kwon & Taiti, 1993 |
8’ | Noduli laterales on pereonite 7 close to lateral margins | 9 |
9 | Noduli laterales on pereonite 1 close to lateral margins (Fig. |
L. subcurvatus Li & Wang sp. nov. |
9’ | Noduli laterales on pereonite 1 much farther from lateral margins (Fig. |
L. formosus Li & Wang sp. nov. |
10 | Male pleopod 1 exopod with inner lobe longer than outer lobe | 11 |
10’ | Male pleopod 1 exopod with inner lobe shorter than outer lobe | 13 |
11 | Male pleopod 1 exopod conspicuously concave at distal apex ( |
L. zavattarii (Arcangeli, 1927) |
11’ | Male pleopod 1 exopod nearly straight at distal apex | 12 |
12 | Antenna flagellum with second segment about twice as long as first one; inner lobe of male pleopod 1 exopod weakly developed ( |
L. xiaoi Nunomura & Xie, 2000 |
12’ | Antenna flagellum with second segment about three time as long as first one; inner lobe of male pleopod 1 exopod well developed ( |
L. minatoi (Nunomura, 1987) |
13 | Epimeron well developed; postero-lateral corner of pereonite 1 acute ( |
L. nudus Li, 2017 |
13’ | Epimeron undeveloped; postero-lateral corner of pereonite 1 nearly right-angled (Fig. |
L. schmidti Li & Wang sp. nov. |
14 | Male pleopod 1 exopod concave at distal apex | 15 |
14’ | Male pleopod 1 exopod not concave at distal apex | 26 |
15 | Distal margin of male pleopod 1 exopod truncated ( |
L. kurehaensis Nunomura, 2013 |
15’ | Distal margin of male pleopod 1 exopod untruncated | 16 |
16 | Male pleopod 1 exopod with inconspicuous outer lobe | 17 |
16’ | Male pleopod 1 exopod with clear outer lobe | 18 |
17 | Apical part of male pleopod 2 exopod short and broad ( |
L tokyoensis Nunomura, 2000 |
17’ | Apical part of male pleopod 2 exopod thin and long ( |
L. toyamaensis Nunomura, 2008 |
18 | ale pleopod 1 exopod with inner lobe as long as outer lobe ( |
L. albulus Nunomura, 2013 |
18’ | Male pleopod 1 exopod with inner lobe not as long as outer lobe | 19 |
19 | Male pleopod 1 exopod inner lobe longer than outer lobe | 20 |
19’ | Male pleopod 1 exopod inner lobe shorter than outer lobe | 21 |
20 | Outer lobe of male pleopod 1 exopod with sinuate margin ( |
L. sagarai Nunomura, 2008 |
20’ | Outer lobe of male pleopod 1 exopod with smooth margin ( |
L. gigliotosi (Arcangeli, 1927) |
21 | Outer lobe of male pleopod 1 exopod with sinuate margin ( |
L. yokohatai Nunomura, 2010 |
21’ | Outer lobe of male pleopod 1 exopod with smooth margin | 22 |
22 | Male pleopod 1 exopod with inner lobe shorter than outer lobe | 23 |
22’ | Male pleopod 1 exopod with inner lobe much shorter than outer lobe | 24 |
23 | Male pleopod 1 exopod with inner lobe narrower than outer lobe, inner lobe ending with seta ( |
L. sinuosus (Nunomura, 1987) |
23’ | Male pleopod 1 exopod inner lobe wider than outer lobe, each lobe ending with seta (Fig. |
L. dianensis Li & Wang sp. nov. |
24 | Male pleopod 1 exopod with well developed inner lobe (Fig. |
L. dissectus Li & Wang sp. nov. |
24’ | Male pleopod 1 exopod with weakly developed inner lobe | 25 |
25 | Male pleopod 1 exopod with inner lobe much wider than outer lobe (Fig. |
L. digitatus Li & Wang sp. nov. |
25’ | Male pleopod 1 exopod with inner lobe as wide as outer lobe (Kwon and Taiti, 1993: fig. 168) | L. isseli (Arcangeli, 1927) |
26 | Male pleopod 1 exopod triangular | 27 |
26’ | Male pleopod 1 exopod not triangular | 28 |
27 | Male pleopod 1 exopod triangular, concave near middle ( |
L. yamamotoi Nunomura, 2013 |
27’ | Male pleopod 1 exopod triangular, not concave near middle ( |
L. latus (Uljanin, 1875) |
28 | Male pleopod 1 exopod ovate | 29 |
28’ | Male pleopod 1 exopod half-moon-shaped | 30 |
29 | Inner margin of male pleopod 1 exopod slightly concave near middle ( |
L. sakimori (Nunomura, 1987) |
29’ | Inner margin of male pleopod 1 exopod not concave near middle ( |
L. kobarii
( |
30 | Outer margin of male pleopod 1 exopod distinctively concave near middle ( |
L. ashiuensis Nunomura, 2010 |
30’ | Outer margin of male pleopod 1 exopod not concave near middle | 31 |
31 | Noduli laterales on pereonites almost at same distance from lateral margins; male pleopod 1 exopod with seta at distal apex ( |
L. nichinanensis Nunomura, 2003 |
31’ | Noduli laterales on pereonites 2–4 shifted from lateral margins than those of pereonites 5−7; male pleopod 1 exopod without seta at distal apex ( |
L. hachijoensis (Nunomura, 1987) |
32 | Posterior lateral margin of pereonite 1 nearly straight | 33 |
32’ | Posterior lateral margin of pereonite 1 convex | 35 |
33 | Male pleopod 1 exopod slightly concave at distal apex ( |
L. pedimaculatus Kwon & Taiti, 1993 |
33’ | Male pleopod 1 exopod concave at distal apex | 34 |
34 | Noduli laterales on pereonites 2–4 shifted from lateral margins than those of pereonites 5−7; male pleopod 1 exopod with inner lobe as long as outer lobe ( |
L. taitii Kwon, 1993 |
34’ | Noduli laterales on pereonites almost at same distance from lateral margin; male pleopod 1 exopod with inner lobe shorter than outer lobe ( |
L. altaicus Gongalsky, Nefediev & Turbanov, 2021 |
35 | Male pleopod 1 exopod concave at distal apex | 36 |
35’ | Male pleopod 1 exopod not concave at distal apex | 37 |
36 | Noduli laterales on pereonites almost at same distance from lateral margins; male pleopod 1 exopod with seta at distal apex of inner lobe ( |
L. boninshimensis (Nunomura, 1987) |
36’ | Noduli laterales on pereonites 2–4 shifted from lateral margins than those of pereonites 5−7; male pleopod 1 exopod with seta at distal apex of outer lobe (Fig. |
L. gracilentus Li & Wang sp. nov. |
37 | Male pleopod 1 exopod with round distal apex ( |
L. punctatus Nunomura, 2013 |
37’ | Male pleopod 1 exopod with triangular distal apex ( |
L. minakatai Nunomura, 2003 |
To date, thirty-eight species are recorded in the genus Lucasioides all over the world, including the new species described herein. As mentioned, all the recorded localities of the genus are from China, Japan, Korea, and Russian Siberia (
The effective taxonomic approaches are essential to explore the species diversity of taxa. To solve the morphological problems of woodlice, DNA-based approach has revealed an effective way for delimiting species boundaries and revealing cryptic taxa (e.g., Karasawa et al. 2014;
As presented here, the first molecular analyses based on a broad sample of Lucasioides (Table S1), supporting the partial COI sequences can be applied as a useful DNA barcode marker for identifying Lucasioides species (Table S2). In molecular species delimitation, ABGD and BPP strongly supported a same species hypothesis, but bPTP and BIN may overestimate the species diversity of the genus (Fig.
In addition, we applied geometric morphometrics to visualize and test the body-shaped differences among the Lucasioides samples using two-D landmarks data. Results demonstrated that canonical variate analysis is superior to principal component analysis (Fig.
Finally, we integrated DNA sequences with morphological evidence to resolve the taxonomic problems, revealing exceptional species diversity of Lucasioides from China and four cryptic species. The results demonstrate that the integrative taxonomy is especially important to reveal the cryptic species among the high morphological similarity of taxa, as well as providing an effective way for species delimitation to accelerate the exploration of woodlice biodiversity.
JW, CJ and WCL contributed to the study conceptualization and design. JW, CHY and WCL identified specimens and produced illustrations and maps. JW carried out the molecular laboratory work under supervision of WCL and CJ. All authors contributed to the draft of the manuscript. All authors read and approved the final manuscript.
We are grateful to Dr. S. Taiti (Istituto per lo Studio degli Ecosistemi, Italy), Dr. C. Schmidt (Senckenberg Naturhistorische Sammlungen Dresden, Germany), Dr. N. Nunomura (Institute of Nature and Environmental Technology, Kanazawa University, Japan), Dr. D. H. Kwon (Inje University, Korea), and Dr. G. M. Kashani (University of Zanjan, Iran) for providing important references and generous help. Special thanks are given to Dr. M. J. Raupach (Bavarian State Collection of Zoology, Germany) and an anonymous reviewer for their insightful suggestions. The research was supported by the National Natural Science Foundation of China (nos. 31960100, 82073972).
Tables S1–S4
Data type: .docx
Explanation notes: Table S1. Description of the samples that were used for phylogenetic analysis, including taxon, DNA number, collection localities, DNA Data Bank of Japan (DDBJ) accession number, and Barcode Index Number (BIN) of the Barcode of Life Data System (BOLD). — Table S2. Percentage of divergence in the cytochrome c oxidase subunit I (COI) gene sequences of the Lucasioides species with outgroups. — Table S3. Percentage of divergence in the 18S rRNA gene sequences of the Lucasioides species with outgroups. — Table S4. Percentage of divergence in the 28S rRNA gene sequences of the Lucasioides species with outgroup.