Eocyzicus palpalis, Simhachalam, Gullipalli & Timms, Brian V, 2012

Simhachalam, Gullipalli & Timms, Brian V, 2012, Two new species of Spinicaudata (Crustacea: Branchiopoda) in south India with a key to Leptestheriella and Eocyzicus, Zootaxa 3161, pp. 20-36 : 28-33

Eocyzicus palpalis sp. nov.

( Figs 4–6 )

Etymology. The specific epithet, palpalis is derived from the characteristic palps on the male fifth endite of the thoracopods VI and VII and the palp on the fourth endite of the thoracopod III.

Type locality. INDIA: Racharla Mandal, Prakasam District. Pool at Racharla (15° 28' N, 78° 58' E) approximately 22 km north of Giddaluru. (altitude 224 m asl). Date of collection: 26 August 2002 by G. Simhachalam.

Type material. Holotype. Male, length 10.1mm; height 7 mm., accession number NHM 2005.277.

Allotype. female length 10.3 mm, height 7.2 mm, accession number NHM 2005.278.

Paratypes. Male of 9.5 mm length and three females of 10.1, 9 and 8 mm length; height: 7, 6 and 5mm respectively. INDIA: Prakasam District, Racharla Mandal. Pool at Kaluvapalli (15° 26'N,78° 58.'E, altitude 224m asl)), approximately 19 km north of Giddaluru. Accession number NHM 2005.278–281. Remainder of the material is deposited In Museum, Department of Zoology, Acharya Nagarjuna University. collected 15 October 2003

Description. Male.

Carapace ( Fig. 4 A), broadly ovate, thin, light yellow, granulose, translucent, umbone prominent, maximum width of carapace just posterior to umbone. Carapace broadly rounded anteriorly and posteriorly; hinge line straight ( Fig. 4 A), forming 20° angle with posterior free margin of carapace. Ventral free margin evenly rounded. Twenty nine growth lines ( Fig. 4 A) lacking spinules or setae, becoming more crowded marginally. Growth line interstices densely and irregularly granulate ( Figs 4 B, D).

Head ( Fig. 4 E), oval in dorsal view, rectangular in lateral view, about 46% of trunk length; eyes oval in lateral view and sub confluent; ocular protuberance large, double the size of eye; ocellus (oc) triangular in lateral view situated in front of eyes. Fornix (fo) well defined, extending to rostral apex. Rostrum (ro) spatulate, slightly inflected; occipital angle obtuse, forming a shallow notch at junction of head to trunk (posterior to eye). Mandibles crescent shaped.

First antenna ( Fig. 4 E) a little shorter than second antenna, reaching second antennal 13th flagellomere. 28 clearly demarcated sensory lobes on left and right ramus, each with several sensory aesthetascs.

Second antenna ( Fig. 4 E) peduncle broad, 1.8 times as long as broad, with indistinct annulae and heavily fringed with short spines anteriorly. Biramal flagellae unequal in size, anterior (apparently dorsal) flagellum of 16 and posterior (apparently ventral) flagellum of 15 flagellomeres. Each flagellomere armed with 2–5 short, serrated spines anteriorly and with 2–4 long slender plumose setae posteriorly.

Trunk with 23 pairs of thoracopods.

Thoracopod I and II modified as claspers ( Figs 4 F,G) distally composed of fourth fifth and sixth endites. Hand (clasper endopod) broad with digitiform apical projection (endite 4) clothed with scales distally and bearing a short small palp distolaterally. Moveable finger curved (endite 5) and apically acute. Large palp (endite 6) digitiform. Thoracopod I hand with asymmetrical swelling peaking near base of apical process. Apical projection diameter 1.1 times its height. Short palp a little shorter than diameter of apical projection and moveable finger, and large palp subequal in length. Large palp 2-segmented, proximal segment nearly double the length of distal segment; distal segment widened toward truncate apex, setae distally. Thoracopod II ( Fig. 4 G) with medial margin of hand much less expanded than in thoracopod I, but apical process and its small palp of similar dimensions as in thoracopod I. Moveable finger similar in the two thoracopods, but large palp about 1.4 times longer than moveable finger. This palp two segmented unequally, proximal segment 1.2 times longer than distal segment, distal segment widened toward truncate apex, setae distally.

Thoracopod III fifth endital palp 4-segmented ( Fig. 5 A), proximal and second segment subequal, proximal segment 1.1 times as long as second segment and 0.4 times fourth endital palp. Distal segment 1.8 times as long as proximal and 3.2 times as long as preceding segment, setae distally.

Thoracopod IV fifth endital palp 3-segmented ( Fig. 5 B), proximal and middle segments equal, distal segment 1.6 times as long as proximal. Distal segment widened toward truncate apex, setae distally. Lack of palp on fourth endite and subsequent thoracopods. Fifth endite’s palp of third and fourth thoracopods almost equal.

Thoracopod V fifth endital palp 2-segmented ( Fig. 5 C), unequal, distal segment 1.7 times as long as proximal segment; distal segment widened toward truncate apex, setae distally.

Thoracopod VI fifth endital palp slender, unsegmented ( Fig. 5 D), 1.2 times as long as sixth endite, setae distally.

Thoracopod VII fifth endital palp much shorter, by 46% of counterpart in sixth thoracopod ( Fig. 5 E), setae distally.

Eight and succeeding thoracopods lack fifth endital palp.

Thirteen posterior most body segments with large sturdy spines dorsally, one per segment.

Telson ( Fig. 6 A), curved dorsally; 24 unequal serrated spines and short spinular outgrowths terminally. Forked hair filament (=telsonic setae) lies between third and fourth spines. Telson ventral margin shorter than dorsal margin and with a pair of furcal claws (= caudal furca or cercopods).

. palpalis sp. nov. 3 L 5.5 – 11 13 – 35 Spatulate 24 – 34 12 – 15/16 –17 22 – 23 24 – 33 2 nd,3rd & 21 – 31 Racharala & H 3.5 – 7 4th Kaluvapalli

Ƥ L 4 – 11.5 14 – 40 Triangular & 24 – 31 11 –14 /15 – 16 21 – 22 20 – 31 3rd,4th & 5th 13 – 28 India H 3 – 8 Obtuse

Furcal claw ( Fig. 6 A) elongate, broader proximally and tapering distally; as long as telson dorsal margin. Dorsally with plumose setae, 35 in number proximally, a spinular spine and many minute spinules distally.

Description. Female.

Carapace similar to that of male, except for broader and more rounded anterior margin; Hinge line straight, not forming angles in anterior and posterior regions on carapace. Twenty nine growth lines.

Head ( Fig. 6 B) conspicuous, oval in dorsal view; eyes sub confluent; ocular protuberance, about 1.2 times greater than eye; occipital angle similar to that of male; occipital notch shallow.

First antenna ( Fig. 6 B) as in male; reaching second antenna 7th flagellomere. First antenna with 25 clearly demarcated sensory lobes on left and right ramus, each with several sensory aesthetascs.

Second antenna ( Fig. 6 B) as in males. Anterior (apparently dorsal) flagellum of 14 and posterior (apparently ventral) flagellum of 15 flagellomeres. Each flagellomere armed with 2–5 short, serrated spines anteriorly and with 2–4 long slender plumose setae posteriorly.

Trunk with 22 pairs of thoracopods. Thoracopod I with 6 endites with deep notches between them; its fifth endital palp 1.1 times as long as endital palp of thoracopod II. Endital palp of thoracopods II and III equal, unsegmented. Fifth endite lacking a palp in remaining thoracopods. All thoracopods otherwise similar except ninth ( Fig. 6 C) and tenth. Thoracopod IX with dorsal lobe of exopod ( Fig. 6 C) elongate, non-setose and three times longer than branchial flabellum. Dorsal lobe of exopod of thoracopod X reduced compared to counterpart in thoracopod IX. Trunk dorsal armature resembles that of male.

Telson curved dorsally. 26 unequal serrated spines. Telsonic filament (telsonic setae) lies between fourth and fifth telson spines. Furcal claw resembles that of male. Dorsally with plumose setae, 27 in number proximally, a spinular spine and many minute spinules distally.

Egg s. Diameter 149.71 ± 9.23 mm (N = 30); spherical ( Fig. 6 D) and light brown; surface with markedly elevated ridges forming polygonal structures connected together in a reticulate fashion. Egg ridges are round and smooth.

Differential Diagnosis. In gross morphology, E. palpalis sp. nov. differs from all Indian Eocyzicus in having a large (> 24) number of first antennal sensory lobes, and also in having a large number (> 21 in male,> 13 in female) of furcal claw plumose setae ( Table 3 ). E. palpalis sp. nov. is most similar to E. plumosus (Royan & Sumitra 1973) , in the general form of carapace, rostrum and telson. E. palpalis sp. nov., however, differs significantly from E. plumosus and the other Indian species in the following characters: the ornamentation of the carapace, the form of the peripheral growth lines, the fifth endite of the sixth and seventh thoracopods bear a palp, and the fourth endite on the third thoracopod bears a palp.

To some extent, the carapace ornamentation of E. palpalis sp. nov. resembles that of the Iraqi E. mesopotamiensis (Mohammad 1985) , however it differs from it in number of growth lines, number of first antenna sensory lobes, number of thoracopods, and plumose setae on furcal claw. E. palpalis sp. nov. can easily be recognized from all the existing species in the following characters: 1) ornamentation of the carapace; 2) the fifth endite of the sixth and seventh thorocopods bear a palp, and fourth endite on the third thorocopod bears a palp and plumose setae.

Ecology. Eocyzicus palpalis sp. nov. was collected from temporary freshwater pools and puddles. Water temperature: 32.2o C; Dissolved Oxygen: 7.3 mg. L -1; pH: 7.8; Chlorides: 172 mg. L -1; Conductivity: 189µS.cm -1; Turbidity: 6.8 NTU; HCO3 -: 58 ppm. Rarely the pool water is used for washing clothes.

Remarks. This species is assigned to the genus Eocyzicus based on the following characters: rostrum exhibits sexual dimorphism; female’s rostrum is triangular and compressed, and in males it is spatulate; the occipital angle is rounded, and occipital notch is shallow. The genus Eocyzicus is represented in India by eight species (plus one unconfirmed species) whose morphological features are summarized in Table 3 .

There are morphological variations within male and female species of Eocyzicus palpalis collected from Racharla and Kaluvapalli. Epizoic algae noticed on older specimens.

In males growth lines number 13–35, with distal growth lines in older specimens irregular, with furrowed interstices; rostrum broad or spatulate. First antenna dorsal lobes range from 24–34; second antenna flagellomeres vary from 12–17; trunk has 22–23 thoracopod pairs; and telson has 24–33 unequal serrated spines. The telsonic filament (telsonic setae) lie between second and third or third and fourth spines. The number of spines on either side of telson within the same specimen often differs. Plumose setae on the furcal claw vary between 21and 31. In females growth lines number 14–40. First antenna dorsal lobes range from 24–31; second antenna flagellomeres vary from 11–16; trunk has 21–22 thoracopod pairs; and telson has 20–31 unequal serrated spines. The telson ic filament (telsonic setae) lie between third and fourth or fourth and fifth spines. Plumose setae on the furcal claw vary between 13 and 28.

Figures

FIGURE 4. Eocyzicus palpalis sp. nov. Male A – G, A, carapace growth lines (gl = growth lines; hl = hinge line); B, carapace showing granulation; C, ventral edge of carapace showing growth lines; D, carapace high magnification; E, head with first and second antenna (a 1 = first antenna; a 2 = second antenna; fo = fornix; h = head; oc = ocellus; ro = rostrum); F, first thoracopod clasper (ap = apical projection; hn = hand; lp = large palp; mf = movable finger; sp = small palp); G, second thoracopod clasper. Scale bars A- 1 mm. E – G 0.5 mm.

FIGURE 5. Eocyzicus palpalis sp. nov. Male A – E, A, third thoracopod endites 4 and 5 showing palp (en 4 = endite 4; en 5 = endite 5, en 6 = endite 6; pa = palp); B, fourth thoracopod endite 5 showing palp (pa = palp); C, D and E, fifth, sixth and seventh thoracopods endite 5 showing palp (pa = palp). Scale bars 0.5 mm.

FIGURE 6. Eocyzicus palpalis sp. nov. Male A, Female B – D. A, telson with furcal claw (t = telson; fc = furcal claw); B, head with first and second antenna (a 1 = first antenna; a 2 = second antenna; h = head); C, ninth thoracopod showing non setose elongated dorsal lobe (d-ex = dorsal lobe of exopod); D, egg. Scale bars 0.5 mm.

Tables

TABLE 3. Comparison of Indian species of the genus Eocyzicus.

	Carapace size (mm)	Growth lines	Rostrum	First antenna sensory lobes	Second antenna flagellomeres	Thoracopo ds	Telsonic spines	Telsonicfila ment	Plumose setae Distribution on furcal claw
E. bouvieri 3 Ƥ E. orientalis 3	L 7.8–11.5 H 4.7–7 L 7.81 – 8 H 4.2 – 4.7 L 5.6 – 9.3 H 4.6 – 6.8	10 – 12 -- 10 – 25	Broad Acute Broad	12 – 16 -- 14 – 24	12 – 14 -- 9 – 14	26 -- 20 – 24	15 -- 22 – 25	3rd & 4th 3rd & 4th	-- Simla Hills, Kumaon, India China and India
E. hutchinsoni 3 Ƥ	L 10.6 x 6.9 L 8.8x5.5	15 12	Not well expanded Acute	14 18	12 – 14 11 – 13	22 --	14 26	--	7 Punjab, India --
E. deterrana 3 Ƥ	L 6.67x-4 H – L 6.6x3.8	14 11	Not well expanded Acute	16 14	11 – 12 --	22 --	12 17	--	4 Punjab, Rawalpindi, Sohawa
E. pellucidus 3	L -- H	--	Spatulate	--	---	19	--	--	12 Rajasthan, India
E. acuta 3 Ƥ E. plumosus 3 Ƥ	L -- H L 4 L 7x4.2 L 6.3x4	-- 9 26 – 28 24 – 28	-- Acute Spatulate Triangular Subacute	-- -- 16 – 18 14 – 16	--- 10 12 – 15 12 – 15	-- 15 19 19	-- 11 – 12 26-28 --	1 & 2 4th &5th	-- Pilani, Rajasthan, India 4 18-21 Tuticorin, India --
E. dhilloni 3 Ƥ E. mesopota miensis 3 Ƥ	L 6.52 H 3.52 L 6.23 H 3.51 L -- H L --	15 14 17 20	Spatulate Triangular Spatulate Triangular	20 -- 20 19	12 – 13 -- 14 – 15 17	19 -- -- 24	28 -- 20 33	5th & 6th --	20 Patiala, Punjab, India -- Iraq -- 9