Urocaridella antonbruunii ( Bruce, 1967 )

Paramasivam, Purushothaman, Madhavan, Manu, Ajith Kumar, T. T. & Lal, Kuldeep Ku- Mar, 2022, New record of Urocaridella antonbruunii (Bruce, 1967) from Southern India with taxonomic Keys of Urocaridella Borradaile, 1915 (Decapoda; Palaemonidae), Zootaxa 5138 (5), pp. 563-574 : 566-570

Species: Urocaridella antonbruunii ( Bruce, 1967)

( Figs. 2–5 )

Periclimenes antonbruunii: Bruce, 1967 , p. 45–53, fig. 19–22; 1971, p. 10

Urocaridella antonbruunii: Chace & Bruce, 1993: 42 . – Bruce & Coombes, 1995: 103. – Bruce, 1996: 203, fig. 1f, 29a, and 31. – Jeng, 1998: 119. – Debelius, 1999: 173. – Davie, 2002: 301. – Li et al., 2004: 525, fig. 13. – Li & Bruce, 2006: 221. – Anker & De Grave, 2016: 428, fig. 108.

Material examined: NBFGR/PALUANT-01 , Female (CL 5 mm), Bay of Bengal , Off Gulf of Mannar , Tamil Nadu, India, 8°42′ N, 78°24′ E, 1–3.0 m depth, December 2019 . Additional: 6 Female CL 3–5 mm, 4 Male CL 3–3.5 mm Off Gulf of Mannar , India, Bay of Bengal. 1 Female CL 6 mm, 1 male CL 4 mm, Lakshadweep Island, India, Arabian Sea, 10°50′ N, 72°10′ E, 0.5–1.0 m feet, November 2019.

Diagnosis: Rostrum ( Fig. 2 ) long, slender, deeply curved upwards, overreaching distal margin of scaphocerite, about 1.5–1.72 times as long as carapace. The rostrum dorsally armed with three pairs of strong teeth (Basal, Middle and Distal) with an epigastric tooth, ventrally armed with 9–10 teeth and long plumose setae ( Figs. 3A, B ). Carapace smooth with a well-developed antennal spine, about 1.5 times as long as broad; orbital angle rounded, ventrally produced a lobe blindly; pterygostomial margin simply rounded; branchiostegal spine prominent, situated far from the anterior margin of carapace. Third abdominal tergite ( Figs. 3C, D ), somewhat sub-rectangular in dorsoposteriorly and laterally compressed; fourth and fifth abdominal tergite normally rounded in dorsoposteriorly, produced leaf-like extension at posteroventrally; sixth abdominal segment elongate, about 2.1–2.25 times as long as the fifth segment with sharp posteroventral angle. Telson ( Figs. 3C, D ) 0.75–0.8 times as long as the sixth abdominal segment with two pairs of movable spines dorsally, three pairs of distal spines on posterior margin. Third maxilliped slender, reaching near to the middle of scaphocerite; penultimate segment about 1.7–1.83 times as long as an antepenultimate segment. The first pereiopod slightly overreached the distal end of scaphocerite, fingers subequal to palm length, carpus about 1.7–1.8 times as long as a chela ( Fig. 4A ). Second pereiopod slender, extended beyond the scaphocerite by chela; fingers almost subequal to palm and shorter than carpus ( Fig. 4B ). Ambulatory pereiopods ( Figs. 4 C-E) are long and slender, propodus with 3–4 ventral spiniform setae with biunguiculate dactylus. The third pereiopod extended beyond the distal part of scaphocerite by half of the carpus and dactylus, carpus about 5.8–6.6 times as long as dactylus. The fourth and fifth pereiopods elongated further on the scaphocerite by the length of carpus and dactylus, carpus about 6.0–7.25 times as long as dactylus.

Colouration in Life: The carapace and abdomen ( Fig. 5 ) are transparent with scattered red and white patches. The rostrum is transparent with red and white bands terminally. Eyes are translucent, eyestalk with few red dots. Antennal scaphocerite is almost transparent with a red margin laterally. The base of the epigastric tooth is red with white patches. Third abdominal tergites produced posterodorsally with vertical white and red bands. Pleopods are fully transparent, pereiopods are semi-transparent with white and red bands. The base of telson and uropods with a red band and white patches dorsally. Inner uropods are transparent with red patches anteriorly. Outer uropods with white and red bands posteriorly.

Distribution and ecology: Urocaridella antonbruunii were initially described from the Comoro Islands (type locality) of the western Indian Ocean. Subsequently, this species was reported widely in the shallow water regions of the Indo-west Pacific Ocean: Kenya, La Reunion, South China Sea, Singapore, Japan, Australia, New Caledonia, Loyalty Islands, Palau and Hawaii. Currently, the distribution of the species was noticed in Indian waters. The present specimens were collected in the bottom curve of the coral boulder at shallow water regions of the Gulf of Mannar and Agatti Island, Lakshadweep. In Agatti Island, these specimens were noticed with the assemblage of U. arabianensis and pipefish ( Doryrhamphus sp ) in the bottom of dead coral.

Remarks: The morphology of U. antonbruunii in the present study is closely agreed with the original description and illustrations of Bruce (1967) from the Comoro Islands with a minute variation on the length and dentition of rostrum, length ratio of carpus and palm of first and second pereiopod and length ratio of propodus and dactylus of ambulatory pereiopods. Furthermore, this is the first report from the Indian waters, especially from Agatti Island, Lakshadweep, and the Gulf of Mannar. Even though, slight variation was noticed between Agatti and Gulf of Mannar specimens, which were intra-specific and noticeable. Agatti specimen have 2+2+2/10 teeth on the rostrum, the ratio of rostrum and carapace was 1.7 and ratio of the telson and sixth abdominal somite was 0.8, wherein specimens of Gulf of Mannar, rostral dentition was 2+2+2/9, rostrum 1.5–1.66 times longer than carapace and telson was 0.75 times as long as the sixth somite. Similarly, the different rostral formula was noticed in many locations for U. antonbruunii , where 2+2+1/ 6 in the Comoro Islands ( Bruce 1967), (1-3) + 2 + (2-3)/ 8 -12 in New Caledonia ( Bruce, 1996), 2 + 2 + (1-2)/ 6-8 in South China ( Li et al., 2004). Also, in the present Indian specimen, the ratio of propodus and dactylus of third pereiopods are slightly higher (5.8–6.6 times) than the previous reports (4–4.5 times; Bruce, 1967, 1996; Li et al., 2004).

Urocaridella antonbruunii is morphologically closest to U. urocaridella , U. cyrtorhyncha , U. pulchella and U. arabianensis . However, the ratio of the rostral and carapace, different segments of the maxilliped, pereiopods and third abdominal dorsal structure have differed between these species. The rostrum length of U. antonbruunii is 1.5–1.72 times as long as the carapace length, which was notably different with U. cyrtorhyncha (1.8 times), U. urocaridella (2.0 times) and U. arabianensis (1.7–2.1 times). The third abdominal dorsal structure is produced triangularly or sub-rectangular profile in U. antonbruunii , whereas expanded and rounded dorsal profile in U. cyrtorhyncha , prominent, rounded, sub-rectangular profile in U. pulchella , nearly sub-rectangular dorsal profile in U. urocaridella and produced dorsoposteriorly and rounded profile in U. arabianensis . The ratio of carpus and palm of first and second pereiopods are 2.8 and 1.26 times in U. antonbruunii which compared 1.5 and 1.0 times for U. cyrtorhyncha , 1.5 times for U. pulchella (Second pereiopod only), 1.0 and much shorter for U. urocaridella , 2.5 and 1.8 times for U. arabianensis , respectively. Moreover, U. cyrtorhyncha is very similar to U. antonbruunii due that Bruce & Coombes (1995) considered Leandrites cyrtorhynchus Fujino & Miyake, 1969 as a synonym of U. antonbruunii ( Bruce, 1967) . However, Okuno (1994) and Hayashi (2000) accepted U. cyrtorhyncha as different species. Furthermore, Ďuriš (2017) found few morphological differences in U. cyrtorhyncha , which have 2 sub-apical dorsal teeth on the rostrum, dactylus of third to fifth pereiopods were not biunguiculated and proximal third of the cutting edge of second pereiopods with a tooth. However, present Indian specimens of U. antonbruunii have 2 sub-apical dorsal teeth on the rostrum, which is similar with the observation of Bruce (1996) and Li et al. (2004).

Figures

FIGURE 2. Urocaridella antonbruunii (Bruce, 1967) (Male, CL 3.5 mm) from Gulf of Mannar, Bay of Bengal, India.

FIGURE 3. Urocaridella antonbruunii (Bruce, 1967) from India. (A) Lateral view of the carapace (female). (B) Lateral view of the rostrum. (C & D) Lateral view of abdominal tergites. (A & C) female, Gulf of Mannar; (B & D) male, Agatti Island.

FIGURE 4. Urocaridella antonbruunii (Bruce, 1967), Male, CL 3.5 mm from India. (A) Lateral view of the first pereiopod. (B) Dorsal view of the second pereiopod. (C-E) Lateral view of third to fifth pereiopods with biunguiculated.

FIGURE 5. Colouration of Urocaridella antonbruunii (Bruce, 1967) from India. (A) Animal in live. (B) Animal in dead (Gulf of Mannar).