Caridina vithuraensis, Vijayamma, Kunjuraman & Thomas, Tessa, 2012

Vijayamma, Kunjuraman & Thomas, Tessa, 2012, Caridina vithuraensis sp. nov. (Decapoda: Atyidae) from Vamanapuram River, Kerala region of Western Ghats, India, Zootaxa 3301, pp. 61-68 : 62-65

Caridina vithuraensis sp. nov.

( Figs. 1 –6)

Holotype: Male, 12.5 mm total length, from Kallar, at Vithura, a tributary of Vamanapuram River, deposited at Zoological Survey of India Western Ghats Regional Centre, Kozhikode —Registration No. ZSI/ WGRC /IR-INU/ 2105

Allotype: Female, 16.5 mm total length, from Kallar, at Vithura, a tributary of Vamanapuram River, deposited at Zoological Survey of India Western Ghats Regional Centre, Kozhikode —Registration No. ZSI/ WGRC /IR- INU/2106

Paratypes: 14 males (11.0–15.0 mm), 3 non-berried females (14.0– 16.5 mm) deposited in the Kerala University of Fisheries and Ocean Studies Museum.

Diagnosis. Small shrimps having short rostrum, extending to the tip of 1st segment of antennular peduncle, rarely reaching beyond, rostral formula: 11–19/2–5 (2–5 post-orbital); carpus of 1st pereiopod deeply excavated, 1.3 to 1.45 times as long as broad; dactylus of 3rd pereiopod ends in a terminal spine and with 5–7 accessory spines; dactylus of 5th pereiopod with 24–45 comb-like spinules; appendix interna on endopod of male 1st pleopod is prominent; uropodal diaeresis with 16–20 spines; telson conical in shape with 4–6 pairs of spinules on the dorsal and 6– 8 spinules at the distal end.

Description. Rostrum short, extending to the tip of 1st segment of the antennular peduncle, rarely reaching beyond; upper margin convex, with 11–19 equidistant teeth progressively decreasing in size towards the distal end, of which 2–5 teeth are post-orbital; distal end of rostrum with a short edentulous gap. Ventral margin with 2–5 teeth, very small or indistinct, confined to distal half. Rostral formula: 11–19/2–5 (2–5 post-orbital). Carapace with antennal spine slightly below the inferior orbital angle; pterygostomian margin rounded ( Fig. 1 A, B).

FIGURE 2. Caridina vithuraensis ; A—Telson, B—Uropod, C—Diaeresis, D—Male 1st pleopod, E—Male 2nd pleopod, F— Female 1st pleopod, G—Preanal carina

Abdomen normal in structure, about 2.3–2.5 times as long as postorbital carapace.

Distal margin of telson rounded, usually without median spine; bears 6–8 distal spines of more or less uniform length, sometimes with 1–2 short median prolongations; dorsal surface with 4–6 pairs of spines (Fig. 2A).

Antennular peduncle 3 segmented; stylocerite 0.74 times the length of basal segment, anterolateral spine of this segment reaching nearly 1/4th of the 2nd antennular segment ( Fig. 3 A). Scaphocerite 3.3–3.7 times as long as wide ( Fig. 3 B).

Incisor process of mandible ending in 4–5 irregular teeth, apophysis strong, molar process truncate ( Fig. 3 C). Endopod of maxillula short, gnathobase of basis consists of 1–2 rows of teeth ( Fig. 3 D). Maxilla typical in structure, scaphognathite tapers posteriorly bearing 19–21 long setae at its distal end ( Fig. 4 A). First maxilliped with a highly setose basis, exopod broad with distal end projected as a slender process; endopod small ( Fig. 4 B). Second maxilliped with a well-developed podobranch ( Fig. 4 C). Dactylus of 3rd maxilliped ends in a large apical spine, its posterior margin bearing 5–6 smaller spines, 2nd and 3rd segments bear several rows of short spinous setae (Fig. 5A).

First pereiopod slender; ischium smaller than merus, merus 2.8–3.0 times as long as broad, 1.2–1.3 times as long as carpus; carpus excavated anteriorly, shorter than propodus, 1.3–1.45 times as long as broad; propodus 1.5– 1.6 times as long as broad; fingers 1.1–1.2 times as long as palm (Fig. 5B).

Second pereiopod slender; ischium smaller than merus, merus 4.3–5.3 times as long as broad, 0.90–1.15 times as long as carpus; carpus 1.25–1.3 times as long as propodus, 4.0–4.4 times as long as broad; propodus 2.0–2.2 times as long as broad; fingers 1.3–1.7 times as long as palm (Fig. 5C).

Third pereiopod slender; ischium longer than dactylus, with or without a spine, merus the longest segment, carries 3–4 spines, carpus with a big sub-terminal spine and an inner row of 3–4 spinules, dactylus ends in a strong claw, bearing on its posterior margin 5–7 accessory spines (Fig. 6A, B).

Fourth pereiopod similar to 3rd; ischium, merus and dactylus bear 0–1, 2–3, and 5–6 spines respectively on the inner margin (Fig. 6C, D).

Fifth pereiopod also slender; ischium longer than dactylus, sometimes bearing a single spine, merus with 2–3 spines, carpus with a big sub-terminal spine and a row of 4 spinules, dactylus ending in a sharp spine, its posterior margin with 24–45 comb-like spinules (Fig. 6E, F). Epipods present on 1–4 pereiopods; two setobranchs each on all pereiopods.

FIGURE 5. Caridina vithuraensis ; A—Maxilliped III, B—1st pereiopod, C—2nd pereiopod Endopod of 1st pleopod of male 0.39 times the length of exopod, appendix interna slightly bent outwards, distinctly overreaching the distal end of endopod (Fig. 2D). Appendix masculina on the male 2nd pleopod armed with stiff setae nearly twice as long as appendix interna, 0.35 times the length of endopod (Fig. 2E). Endopod of 1st pleopod of female slender, 0.84–0.86 times the length of exopod (Fig. 2F). Pleopods 2–5 normal. Uropodal diaeresis with 16–20 movable spines (Figs. 2B, C).

Preanal carina pronounced with a few setae (Fig. 2G).

Measurements. Holotype (male)—Total length 12.5 mm, Carapace length 4.25 mm, Cephalothoracic length 3.4 mm, Rostral length 0.8 mm, Telson length 1.9 mm. Allotype (female)—Total length 16.5 mm, Carapace length 5.5 mm, Cephalothoracic length 4.25 mm, Rostral length 1.2 mm, Telson length 2.0 mm.

Etymology. The species name is derived from the type locality—Vithura, Trivandrum District, Kerala.

Figures

FIGURE 1. Caridina vithuraensis; A, B—Carapace showing variations in the nature of rostrum

FIGURE 3. Caridina vithuraensis; A—Antennule, B—Antenna, C—Mandible, D—Maxillula.

FIGURE 4. Caridina vithuraensis; A—Maxilla, B—Maxilliped I, C—Maxilliped II