Paralebbeus jiaolongi, Xu & Liu & Ding & Wang, 2016

Xu, Peng, Liu, Feng, Ding, Zhongjun & Wang, Chunsheng, 2016, A new species of the thorid genus Paralebbeus Bruce & Chace, 1986 (Crustacea: Decapoda: Caridea) from the deep sea of the Northwestern Pacific Ocean, Zootaxa 4085 (1), pp. 119-126 : 120-124

publication ID	https://doi.org/ 10.11646/zootaxa.4085.1.5
publication LSID	lsid:zoobank.org:pub:03585218-3AF9-43ED-B4B7-10C3D091DAAC
DOI	https://doi.org/10.5281/zenodo.6059203
persistent identifier	https://treatment.plazi.org/id/742F87C6-FFC3-FF84-FF15-FEF8E9C5F8B6
treatment provided by	Plazi
scientific name	Paralebbeus jiaolongi
status	sp. nov.

Treatment

Paralebbeus jiaolongi sp. nov.

( Figs. 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )

Material examined. Holotype: ovigerous female, cl 10.2 mm, 15°40.98′N, 154°55.38′E, near the Caiwei Seamount , Northwestern Pacific Ocean, 1600–1800 m, with sponge specimens collected by “ Jiaolong ” submersible, 25 July, 2014. GoogleMaps

Paratype: male, cl 4.5 mm, same data as holotype.

Description. Holotype female. Rostrum ( Figs. 1 View FIGURE 1 , 2A View FIGURE 2 ) about one-third length of carapace, nearly straight, slightly ascending, reaching about the midpoint of basal segment of antennular peduncle; dorsal margin without any tooth; ventral margin armed with only one subterminal tooth, giving rostrum bifid appearance.

Carapace ( Figs. 1 View FIGURE 1 , 2A View FIGURE 2 ) with strong supraorbital tooth, well-developed antennal tooth and conspicuous pterygostomial tooth; anterolateral margin between antennal and pterygostomial teeth sinuous with deep concavity just inferior to antennal tooth.

Pleuron ( Fig. 1 View FIGURE 1 ) rounded dorsally. Second abdominal somite with shallow transverse groove on tergum. Pleurae of anterior four abdominal somites rounded; fifth pleura with moderately strong posteroventral tooth. Sixth somite 1.4 times as long as fifth mid-dorsal length; posterolateral process terminating acutely. Telson ( Figs. 1 View FIGURE 1 , 2B View FIGURE 2 ) about 1.7 times longer than sixth abdominal somite; bearing 4 pairs of dorsolateral spines, 2.8 times longer than greatest width, with broad, roundly posterior margin ( Fig. 4A View FIGURE 4 ) bearing 2 pairs of markedly unequal lateral spines and 10 setulose spiniform setae.

Eye ( Fig. 1 View FIGURE 1 ) subpyriform; cornea with distinct ocellar spot, shorter than stalk, its maximum width 0.15 of carapace length.

Antennular peduncle ( Fig. 1 View FIGURE 1 ) almost reaching distal end of antennal scale. First segment ( Fig. 2C View FIGURE 2 ) distinctly longer than distal two segments combined, slightly overreaching midpoint of antennal scale, distal margin armed with 2 acute teeth laterally; stylocerite falling short of distal margin of first segment. The distal two segments each with a distinct spiniform distal tooth. Outer flagellum stout and heavily setose. Inner flagellum slender, shorter than outer flagellum, with 27–29 segments.

Antennal peduncle ( Fig. 1 View FIGURE 1 ) with basicerite bearing moderate distal, ventrolateral tooth, dorsodistal angle bluntly produced. Carpocerite overreaching first segment of antennular peduncle. Antennal scale ( Fig. 2D View FIGURE 2 ) nearly half length of carapace, 2.3 times as long as wide; lateral margin nearly straight; with distolateral tooth slightly overreaching rounded distal margin of lamella.

Mouthparts ( Figs. 2E– 2I View FIGURE 2 ) typical of genus. Mandible ( Fig. 2E View FIGURE 2 ) with two-segmented palp; incisor process slender, with a series of five subequal, tiny, distal teeth; molar process stout.

Third maxilliped ( Fig. 3A View FIGURE 3 ) long, half length of penultimate segment beyond antennal scale; ultimate segment 3.1 times as long as penultimate segment, with 6 corneous spines distally; antepenultimate segment subequal in length to ultimate segment; penultimate segment short. Exopod absent and epipod present.

First to third pereopods also with strap-like, terminally hooked epipods.

First pereopod ( Fig. 3B View FIGURE 3 ) stout, overreaching distal margin of antennal scale by about half length of carpus. Chela about 2.4 times as long as carpus, 4.9 times as wide; dactylus with bifid tip, shorter than half length of palm; palm subcylindrical, 3.8 times as long as wide, fixed finger terminating in single corneous claw. Carpus about 2.3 times longer than wide. Merus subequal in length to palm, 4.1 times as long as wide.

Second pereopod ( Fig. 3C View FIGURE 3 ) overreaching antennal scale by about whole length of carpus; carpus divided into 7 articles, third proximal article longest. Merus subequal in length to ischium, 10 times as long as wide.

Third to fifth pereopods moderately long and slender, similar in shape but increasing in length and width toward anterior ( Figs. 3D–3F View FIGURE 3 ). Third pereopod ( Fig. 3D View FIGURE 3 ) overreaching antennal scale by 0.6 length of propodus; biunguiculate dactylus ( Fig. 3G View FIGURE 3 ) about 0.1 times as long as propodus, about 2.8 times longer than high, armed with three accessory spines along entire length of flexor margin; propodus 15 times as long as wide; flexor margin with about 18 spinules, spinules increasing in size distally; carpus less than half length of propodus, 3.5–4.4 times longer than wide. Merus slightly longer than propodus, 8.6 times longer than deep, unarmed.

Fourth pereopod ( Fig. 3E View FIGURE 3 ) overreaching antennal scale by 0.3 length of propodus; flexor margin of propodus with about 15 spinules; merus unarmed. Fifth pereopod ( Fig. 3F View FIGURE 3 ) reaching distal margin of antennal scale; flexor margin of propodus with about 13 spinules; merus unarmed.

Protopods of pleopods each with fairly expanded lateral lobe ( Fig. 1 View FIGURE 1 ). Uropods exceeding telson ( Fig. 1 View FIGURE 1 ).

Eggs large, 2.4 × 2.6 mm.

Paratype male ( Figs. 4B–4D View FIGURE 4 ). Very similar to holotype female. Second pleopod with appendix masculine ( Fig. 3H View FIGURE 3 ) moderately stout, almost 4 times as long as wide, about 0.7 length of appendix interna, bearing about 8 long stiff setae.

Coloration in life. Body mainly transparent, abdomen and caudal fan reddish speckled; antennae whitish; cornea black; third maxilliped and pereopods reddish except the palm of the first pereopod and ambulatory pereopods whitish; intrathoracic organs orange; pleopods whitish ( Figs. 4B & 4C View FIGURE 4 ).

Distribution. Associated with sponges, known only from the deep sea of the Northwestern Pacific Ocean, at depths of 1600–1800 m.

Etymology. The specific name of this new species comes from the Chinese manned submersible “Jiaolong”, in recognition of its successful expedition to the deep sea of the Northwestern Pacific Ocean.

Remarks. The carapace bearing a distinct supraorbital tooth, the absence of postrostral tooth on the carapace, third maxilliped without exopod, third segment of antennular peduncle with sharp dorsodistal tooth, meri of the last three pairs of pereopods without any lateral spines easily classify this species into the genus Paralebbeus Bruce & Chace, 1986 .

The new species can be distinguished from P. mollis Komai, 2013 by the following characeristics. P. jiaolongi armed with only one subterminal tooth on the ventral margin of the rostrum while P. mollis armed on both dorsal and ventral margins of the rostrum. Telson with 4 pairs of dorsolateral spines and roundly posterior margin bearing 10 setulose spiniform setae in P. jiaolongi while telson with 3 pairs of dorsolateral spines and truncated posterior margin with 7 setulose spiniform setae in P. mollis .

Besides the ventral margin of the rostrum being armed with one subterminal tooth, P. jiaolongi has a more strongly developed first pereopod, which overreaches distal margin of the antennal scale by about half of the length of the carpus. However, the rostrum is unarmed and only about the dactylus of the first pereopod reaches beyond the distal margin of the antennal scale in P. zotheculatus .

Rostrum unarmed, supraorbital tooth vestigial or absent, telson with 1–3 (less than 4) dorsolateral teeth on each side, ultimate segment of third maxilliped with about 18 (more than 10) corneous spines distally. These above-mentioned morphological features of P. zygius Chace, 1997 make an obvious distinction between P. zygius and the new species.

Although the reduction of armature on the body parts and appendages is considered to represent the evolutionary trend of adaptation to a life using narrow spaces in host animals, such as sponges, bivalves, and tunicates ( Bruce 1976), Bruce & Chace (1986) as well as Komai (2013) differentiated Paralebbeus from Lebbeus mainly by the absence of postrostral teeth on the carapace and the unarmed meri of the last three pereopods. Just like the previous species of the genus, P. jiaolongi was also found to be associated with an unidentified hexactinellid sponge ( Fig. 5 View FIGURE 5 ).