Hippolyte singaporensis, Gan & Li, 2017

Gan, Zhibin & Li, Xinzheng, 2017, A new species of the genus Hippolyte (Decapoda: Caridea: Hippolytidae) from Singapore, Raffles Bulletin of Zoology 65, pp. 207-212 : 207-211

Hippolyte singaporensis spec. nov.

( Figs. 1–4 )

Material examined. Holotype: 1 ovigerous female, 0.9 mm CL, ZRC 1979.4.28.132, Singapore, Coll. R. u. G., 28 March 1967 . Paratypes: 2 ovigerous females, 0.8–1.0 mm CL, 2 female, 0.7–0.9 mm CL, ZRC 1979.4.28.133–136, Singapore, Coll. R. u. G., 28 March 1967 ; 1 ovigerous female, 1.1 mm CL, ZRC 1979.4.28.129, Changi , Singapore, Coll. Lim Bee Cheng, 27 March 1967 ; 3 ovigerous females, 0.7–0.9 mm CL, 1 female, 0.7 mm CL, 1 male, 0.6 mm CL, ZRC 1979.4.28.122–126, Changi, Singapore, Coll. D. S. Johnson, 26 August 1957 ; 2 males, 0.6–0.7 mm CL, ZRC 1979.4.28.137–138, Singapore, Coll. Lim Bee Cheng, 18 May 1967 ; 15 ovigerous females, 0.7–1.0 mm CL, 7 females, 0.6–0.8 mm CL, 5 males, 0.5–0.7 mm CL, ZRC 1979.4.28.189–215, Tg. Teritip, Singapore, Coll. Lim Bee Cheng, 29 March 1967 ; 8 ovigerous females, 0.7–1.0 mm CL, 14 females, 0.6–0.9 mm CL, 4 males, 0.5–0.7 mm CL, ZRC 1979.4.28.80–105, Singapore, Coll. Lim Bee Cheng, 28 April 1967 .

Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, China; University of Chinese Academy of Sciences, Beijing 100049, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, Qingdao 266200, China; Email: [e-mail] (* corresponding author)

Description. Very small-sized shrimp (0.5–1.1 mm CL in present material) with normal body form ( Fig. 1A ). Ratio lateral length/height of carapace 1.2–1.6. Rostrum ( Figs. 1B , 2A ) slender, 7.3–7.6 times as long as high, straight, slightly shorter or longer than carapace length, distinctly falling short of antennular peduncle apex. Rostrum without lateral carina, without dorsal tooth, with only one ventral tooth in distal position. Carapace smooth and glabrous, with robust supraorbital spine, antennal spine and hepatic spine ( Figs. 1A , 2A ). Base of supraorbital spine posterior to posterior orbital margin. Tip of antennal spine slightly overreaching inferior orbital angle. Base of hepatic spine nearly situating at anterior edge of carapace. Inferior orbital angle strongly produced; pterygostomian region rounded, not produced ( Figs. 1A , 2A ).

© National University of Singapore

ISSN 2345-7600 (electronic) | ISSN 0217-2445 (print)

Abdominal segments smooth ( Fig. 1A ). Third abdominal segment geniculately curved. Ratio dorsal length/height of the sixth abdominal segment 1.5–1.7. Telson ( Fig. 2B ) distinctly longer than sixth abdominal segment; posterior margin rounded, armed with eight strong spines, outer spines smallest, medial two longest, without intermediate spinules. Dorsal surface armed with two pairs of spines situated on distal 0.2 and 0.4 telson length.

Eye ( Figs. 1A, 1B ) well developed; unpigmented part of eyestalk slightly longer than broad; cornea semispherical, reaching stylocerite apex when extended forward; cornea shorter than unpigmented part of eyestalk.

Antennular peduncle ( Figs. 1B , 2C ) reaching proximal 0.8–0.9 length of scaphocerite. First segment of antennular peduncle with only one distolateral tooth, distinctly longer than second and third segments combined; inner ventral tooth on middle-length of first segment (excluding distolateral tooth); stylocerite reaching 0.6 (distolateral tooth included), or 0.7 (distolateral tooth excluded) of first segment. Second segment of antennular peduncle 1.5 times as long as broad in dorsal view, approximately 1.2 times as long as third segment in dorsal view. Outer antennular flagellum shorter and thicker than inner. Scaphocerite ( Fig. 2D ) 2.6–2.8 times as long as wide; distolateral spine of scaphocerite terminating well short of distal margin of blade; distolateral spine and blade separated by notch.

Mouthparts typical for genus. Mandible ( Fig. 3A ) without palp, incisor process with three acute teeth, molar process without teeth. Maxillula ( Fig. 3B ) with simple curved palp, upper lacinia broad, distal margin armed with 13–15 spines and two plumose setae. Maxilla ( Fig. 3C ) with simple palp; lateral border of scaphognathite slightly convex; inner lacinia bilobed, distal margin furnished with row of spines; proximal endite well developed, with simple setae on distal margin. Epipod of first maxilliped ( Fig. 3D ) with outer margin continuous; palp slender, outer margin with long simple setae; exopod with well-developed flagellum, bearing long simple setae at apex; caridean lobe feebly developed; basal endite broad, mesial margin incised, outer margin setose. Second maxilliped ( Fig. 3E ) with epipod deeply bilobed; exopod well-developed, with long simple apical setae; endopod normal, dactylar segment short but broad, terminal margin furnished with spinous setae; propodal segment with anteromedial margin slightly produced, outer margin bearing simple setae; carpus smaller than merus; ischium and basis fused, outer margin furnished with long plumose setae. Third maxilliped ( Fig. 3F ) reaching about 0.5–0.6 of scaphocerite when extended forward; ultimate segment (excluding apical spine) 1.9–2.0 times as long as penultimate segment, distal 0.4 of ultimate segment with eight to nine strong spines; antepenultimate segment slightly shorter than ultimate segment and penultimate segment combined; exopod long, nearly reaching distal margin of antepenultimate segment.

First pereiopod ( Fig. 4A ) moderately robust, slightly overreaching basicerite when extended forward. Basis and merus furnished with few long plumose setae. Cutting edges of fingers of chela not denticulate, but with tiny setula and long simple apical setae; tip of fixed finger with three tiny spines; tip of dactylus with four tiny spines ( Fig. 4B ).

Second pereiopod ( Fig. 4C ) not reaching distolateral spine of scaphocerite when extended forward. Carpus with three subsegments, first segment longest, about 1.4–1.5 times as long as second segment, third segment slightly shorter than or subequal to first segment; first segment 2.7 times as long as wide; second segment 1.6 times as long as wide; third segment 2.1 times as long as wide. Cutting edges of fingers of chela not denticulate, tip of fixed finger and dactylus armed with three tiny spines ( Fig. 4D ).

Third to fifth pereiopods long and robust. Third pereiopod ( Fig. 4E ) reaching beyond terminal blade of scaphocerite by dactylus when extended forward. Dactylus of third pereiopod with 8–11 spines; all spines in ventral or apical position (none in dorsal or subdorsal position); two large apical spines, ultimate one strongest and longest. Propodus 7.8 times as long as wide, armed with five to seven pairs of spines on ventral margin, the spines considerably increasing in size from proximal to distal pair. Carpus 3.5 times as long as wide, armed with one proximal lateral spine. Merus of third pereiopod 5.5 times as long as wide, armed with two lateral spines. Ratio length of third pereiopod dactylus with longest apical spine/length of propodus 0.5; ratio length of third pereiopod dactylus with longest apical spine/length of carpus 1.1; ratio length of dactylus without spines/breadth of dactylus without spines 3.3; ratio length of dactylus with longest spines/breadth of dactylus without spines 5.7; ratio length of longest spine of dactylus/breadth of dactylus without spines 2.7. Fourth and fifth pereiopods ( Fig. 4F, G ) similar in shape to third pereiopod, but slightly decreasing in size. Merus of fourth pereiopod armed with one lateral spine; merus of fifth pereiopod without lateral spine.

Sexual dimorphism. Propodus and dactylus of third pereiopod of male specimens forming a prehensile apparatus ( Fig. 4H ). Appendix masculina with six apical setae, about half length of appendix interna ( Fig. 4I ).

Colouration. Unknown.

Habitat. All specimens were collected at low tide level. The holotype was captured among seagrass bed ( Enhalus acoroides [Linnaeus f.] Royle, 1839); paratypes ZRC 1979.4.28.189–215 were captured among gulfweed ( Sargassum sp.) ; paratypes ZRC 1979.4.28.137–138 were captured among Padina sp .

Etymology. The new species is named after its type locality, Singapore.

Distribution. Currently only known from the type locality, Singapore.

Figures

Fig. 1. Hippolyte singaporensis spec. nov. Ovigerous female holotype, ZRC1979.4.28.132, lateral view. Scales: 1 mm.

Fig. 2. Hippolyte singaporensis spec. nov. Ovigerous female holotype, ZRC1979.4.28.132. A, carapace and rostrum, lateral; B, telson and uropods, dorsal; C, right antennula, dorsal; D, right scaphocerite, dorsal. Scales: 1 mm.

Fig. 3. Hippolyte singaporensis spec. nov. Ovigerous female holotype, ZRC1979.4.28.132. A, left mandible; B, left maxillula; C, left maxilla; D, right first maxilliped; E, right second maxilliped; F, left third maxilliped. Scale: 1 mm.

Fig. 4. Hippolyte singaporensis spec. nov. Ovigerous female holotype, ZRC1979.4.28.132 (AE). Male paratype, ZRC1979.4.28.133 (F, G). A, right first pereiopod, lateral; B, tip of the right first pereiopod, mesial (setae not shown); C, right second pereiopod, lateral; D, tip of the right second pereiopod, mesial (setae not shown); E, left third pereiopod, lateral; F, left fourth pereiopod, lateral; G, left fifth pereiopod, lateral; H, propodus and dactylus of left third pereiopod, lateral; I, endopod of right second pleopod, lateral. Scales: A, C, E–I, 1 mm; B, D, 5 mm.