Caridina cavernicola Liang & Zhou, 1993

Guo, Guo-Cai, Chen, Qing-Hua, Chen, Wen-Jian, Cai, Chao-Huang & Guo, Zhao-Liang, 2022, Caridina stellata, a new species of atyid shrimp (Decapoda, Caridea, Atyidae) with the male description of Caridina cavernicola Liang & Zhou, 1993 from Guangxi, China, ZooKeys 1104, pp. 177-201 : 177

Caridina cavernicola Liang & Zhou, 1993

Figs 4B-D, F-H , 8 , 9

Caridina cavernicola Liang & Zhou, 1993: 232-234, fig. 2 (1-8). [type locality: Lenggu Cave, Du’an Yao Autonomous County, Guangxi]

Caridina cavernicola Liang 2004: 204-206, fig. 98.

Material examined.

Nine males, cl 5.2-7.1 mm, 10 females, cl 5.5-7.8 mm (FU, 2018-11-26-02), Dading Village , Desu Town in the Du’an Chengjiang National Wetland Park (23°56'29"N, 108°0'5"E, alt. 156.17 m), 26 November 2018.3 males, cl 5.0- 6.2 mm, five females, cl 5.6-8.1 mm (FU, 2018-11-26-02), near skylight 3, the Du’an Chengjiang National Wetland Park (24°0'11"N, 107°59'13"E, alt. 162.80 m), 26 November 2018 . Two males, cl 4.7-5.2 mm, four females, cl 5.2-6.8 mm (FU, 2018-11-26-02), skylight 2, the Du’an Chengjiang National Wetland Park (24°0'24.04"N, 107°59'3.81"E, alt. 150.00 m), 26 November 2018 .

Description.

Body: slender and sub-cylindrical, males up to 35.3 mm tl, females up to 40.2 mm tl.

Rostrum (Fig. 8A ): Long, conspicuously high, tip slightly upturned, beyond one-thirds of rostrum and beyond distal end of scaphocerite; 0.91-1.1 of cl; rostrum formula 7-10+21-33/20-29.

Carapace (Fig. 8A ): Smooth, glabrous; antennal spine acute, fused with inferior orbital angle; pterygostomian margin rectangularly rounded, pterygostomian spine absent.

Antennule (Fig. 8B ): Peduncle reaching distinctly short of scaphocerite; stylocerite reaching 0.91 of 1st segment; anterolateral angle reaching 0.40-0.5 of 2nd segment; basal segment shorter than combined length of 2nd and 3rd segments, 2nd segment about 0.51 of 1st segment, about 1.2 of 3rd segment; all segments with marginal plumose setae.

Antenna (Fig. 8C ): Peduncle about 0.32 × as long as scaphocerite; scaphocerite about 3.2-3.4 × as long as wide, outer margin straight, asetose, ending in a strong sub-apical spine, inner and anterior margins with long plumose setae.

Mouthparts as in figure. Mandible (Fig. 8D ) without palp; left incisor process with five sharp teeth; with two groups of medial setae; molar process ridged. Maxillula (Fig. 8E ) with lower lacinia broadly rounded, with several rows of plumose setae; upper lacinia elongate, medial edge straight, with 23-27 strong spinules and simple setae; palp simple, slightly expanded distally, with numerous long simple setae. Maxilla (Fig. 8F ) with scaphognathite tapering posteriorly, with regular row of long plumose setae distally and short marginal plumose setae continuing down proximal triangular process, furnished with numerous long plumose setae; upper and middle endite with marginal simple, denticulate and submarginal simple setae, with distal plumose setae; lower endite with long simple marginal setae; palp slightly shorter than the cleft of upper endite, wider proximally than distally, setose. First maxilliped (Fig. 8G ) with broad palp and with terminal plumose setae; caridean lobe broad, with marginal plumose setae; exopodal flagellum well developed, with marginal plumose setae distally; ultimate and penultimate segments of endopod indistinctly divided; medial and distal margins of ultimate segment with marginal and sub-marginal rows of simple, denticulate and plumose setae; penultimate segments with marginal long plumose setae. Second maxilliped (Fig. 8H ) with ultimate and penultimate segments of endopod indistinctly divided, reflected against basal segment; inner margin of ultimate, penultimate and basal segments with long setae of various types; exopod flagellum long, slender with marginal plumose setae distally. Third maxilliped (Fig. 9A ) reaches to middle of 3rd antennular peduncle segment, endopod three-segmented, penultimate segment about 1.3 × as long as basal segment; distal segment 0.79 × as long as penultimate segment, ending in a large claw-like spine surrounded by simple setae, preceded by five spines, proximally a clump of long and short simple, serrate setae; exopod long, reaches to half of penultimate segment of endopod, distal margin with long plumose setae. Epipods on first four pereiopods.

First pereiopod (Fig. 9B ): Reaches to about end of eye; chela 1.4-2.2 × as long as high; 1.7-1.9 × length of carpus; movable finger 2.4-2.6 × as long as wide, 0.50-0.67 × length of palm, setal brushes well developed; carpus excavated disto-dorsally, 1.3-1.7 × as long as wide, 1.1-1.2 × length of merus.

Second pereiopod (Fig. 9C ): Reaches to about end of 2nd antennular peduncle segment, more slender and longer than first pereiopod; chela 2.1-2.3 × as long as high; 0.97 × length of carpus; movable finger 2.9 × as long as wide and 0.91 × as long as palm, setal brushes well developed; carpus 3.3-4.2 × as long as wide, excavated distally, about 1.2 × length of merus.

Third pereiopod (Fig. 9D ): Reaches beyond end of scaphocerite; dactylus about 3.3 × as long as wide, ending in prominent claw-like spine surrounded by simple setae, behind which are 4-5 spines; propodus 4.9-6.4 × length of dactylus, bearing a row thin spinules on posterior and lateral margin, about 12.1 × as long as wide; carpus about 0.68 × length of propodus; merus 1.6-1.9 × length of carpus, with about 3 strong spines on the posterior margin.

Fourth pereiopod (Fig. 9E ): Reaches middle of 2nd segment of antennular peduncle; dactylus 4.8-5.2 × as long as wide, ending in prominent claw-like spine surrounded by simple setae, behind which is a comb-like row of 61-69 spines; propodus 3.6-4.4 × length of dactylus, bearing a row of spinules on posterior and lateral margins, 16.5-17.1 × as long as wide; carpus 0.50-0.54 × length of propodus; merus 1.3-1.5 × length of carpus, with about three strong spines on the posterior margin.

First pleopod (Fig. 9F ): Endopod in male short, rectangle, about 0.26 × length of exopod, about 1.7 × as long as proximally wide, tip concave, inner margin bearing equal two thin spine setae, outer margin bearing nearly equal long and dense spine setae, without an appendix interna.

Second pleopod (Fig. 9G ): Endopod about 0.83 × length of exopod; appendix masculina rod-shaped, reaching about 0.49 × length of endopod, inner margin and tip bearing nearly equal spine setae; appendix interna well developed, almost the same size as appendix masculina, reaching about 0.97 × length of appendix masculina, with many cincinuli distally.

Telson (Fig. 9H ): 0.44-0.51 × length of cl, distinctly longer than sixth abdominal segment, posterior margin acutely triangular, with a projection, dorsal surface with 6-7 pairs of stout movable spine setae including the pair at posterior lateral angles; posterior margin with four pairs of intermedial plumose setae, lateral pair of spines subequal to intermedian pairs. Exopodite of the uropod bears a series of 12-15 movable spinules along the diaresis.

Eggs 0.80-0.92 × 1.37-1.40 mm in diameter.

Colouration.

Body translucent, rust brown, with small red pigment spots scattered on whole body, with a broad red-brown vertical stripe on each abdominal segment; appendages transparent (Figs 4B-D ).

Remarks.

Caridina cavernicola was known from only two females and one juvenile specimen when it was first collected from a limestone cave in Lenggu Cave, Du’an Yao Autonomous County, Hechi City, Guangxi. Only the name of the cave is mentioned without detailed environmental information and body colour of the shrimps ( Liang and Zhou 1993). Attempts to find the Lenggu Cave through enquiring the exact location from local government departments and residents was unfruitful. However, it was most fortunate that we have collected samples from three sites inside the Chengjiang National Wetland Park. This species is abundant amongst leaf litter and the fibrous roots of riparian trees and plants along the edges of the Chengjiang River. It was also found in small populations in a skylight. No difference was found between individuals collected from the river and skylight sites. We can speculate that the underground water of the skylight may be connected to the Chengjiang River. This also indicates that the shrimp likely only recently invaded the cave environment and can occupy both epigean and hypogean karst habitats.

Liang (2004) mentioned the status of this species as questionable due to some unusual characters, such as: 1st, 2nd pereiopod chela stout; 2nd pereiopod carpus disto-dorsally excavated; 3rd, 4th, 5th pereiopod propodus posterior margin with numerous long plumose setae. Through this study, however, we have found that the morphological and genetic data are congruent and that this species clearly belongs to the genus Caridina .

Ecological notes.

Chengjiang National Wetland Park is located in Du’an Yao Autonomous County, Hechi City, Guangxi. It is also a part of the Du’an Subterranean River National Geopark, Guangxi. The Park mainly consists of the Chengjiang River and integrated farming wetland, river wetland and urban wetland, covering a total area of 8.64 km2, with a width of 11.7 km and a length of 24.2 km. Chengjiang River originates from two skylights, one is Yantan Pool, located at the foot of Guanyin Mountain in Jiudun Village, Daxing Town, the other is Dongtan Pool, located in Taiyang Village, Daxing Town. Chengjiang River belongs to the Red River system, one of the tributaries of the Pearl River system. The river is 50-80 m wide and 5-10 m deep. Chengjiang River and its associated wetlands are also home to many other rare and endangered endemic species of plants and animals. The seaweed flower, Ottelia acuminate is an endangered aquatic plant that is only found in China (Yunnan, Guizhou, Guangxi and Hainan) and can be found in Chengjiang River. Peach blossom jellyfish, Craspedacusta sp., appears in skylight 1 at Zhuqing Tun, Dongmiao Village, Dongmiao Township. The teleostean fish, Metzia formosae is listed as vulnerable (VU) in the China Red Data of endangered animals: fishes ( Yue and Chen 1998) and is also found here. Yunnanilus pulcherrimus , Aphyocypris pulchrilineata , Metzia longinasus , Silurus duanensis and Bibarba bibarba are endemic species of Du’an County ( Ye et al. 2016).

Caridina cavernicola were caught alongside Neocaridina palmata ( Shen 1948) and Macrobrachium nipponense in river sites.

Distribution.

Know from Guangxi Zhuang Autonomous Region, southwest China.

Figures

Figure 4. Habitats and live colouration of Caridina stellata sp. nov. and C. cavernicola A C. stellata sp. nov. B-D C. cavernicola; E-H surrounding environment of C. stellata sp. nov (E) and C. cavernicola (F-H).

Figure 8. Caridina cavernicola A carapace and cephalic appendages, lateral view B antennule C antenna D mandible E maxillula F maxilla G first maxilliped H second maxilliped. Scale bars: 1.0 mm (A); 0.5 mm (B-C); 0.2 mm (D-H).

Figure 9. Caridina cavernicola A third maxilliped B first pereiopod C second pereiopod D third pereiopod E fourth pereiopod F first pleopod G second pleopod H telson I diaeresis of uropodal exopod. Scale bars: 0.5 mm (A-E, H); 0.2 mm (F, G, I).