Leptestheria gurneyi, Padhye, Sameer & Ghate, Hemant V., 2016

Padhye, Sameer & Ghate, Hemant V., 2016, A new species of Leptestheria (Crustacea: Branchiopoda: Spinicaudata) from Western Maharashtra, India, Zootaxa 4127 (2), pp. 345-354 : 346-351

Leptestheria gurneyi sp. nov.

( Figs. 1–5 )

Etymology. The species is named after Robert Gurney who contributed significantly to the Branchiopoda taxonomy of India during early 1900s.

Type locality. A small and shallow rock pool (depth of about 30 cm) on Devi Hasol lateritic plateau (16.7393 N, 17.4324 E), observed during the monsoon season (June–September). The pool had a fine layer of mud but had no aquatic vegetation at the time of collection. No other large branchiopods were observed but few aquatic bugs and beetles were seen.

Type material. Holotype. One male (in 4% formalin + glycerin) deposited at the Western Regional station of Zoological Survey of India (ZSI), Pune (Registration number: ZSI, WRC-C.1520).

Other material. Two males, three females from the type locality in personal collection of SMP. Collector: Ms. Shruti Paripatyadar

Diagnosis: Occipital condyle conical, shorter in male than female. Occipital notch at least twice as wide in female as compared to male. Telson with three distinct size and shape classes of spines with largest at least three times longer than the shortest, 2–6 small spines interspersed in between medium spines, cercopods straight in both sexes, about 0.8 times the dorsal margin of telson in length.

Description. Male. Head. Occipital condyle length about 0.7 times basal breadth, blunt apex directed posteriorly, occipital notch shallow but wide ocular tubercle convex, compound eyes large, almost filling tubercle space, ocellus roughly cylindrical in shape and located at rostral base, rostrum broad, spatulate, fornix prominent, arising from rostrum dorsal angle, ( Fig. 3 C; Fig. 5 A). Rostrum with single sharp spine, three times longer than basal width.

First antenna. Long, more than twice length of second antenna peduncle, about 10–12 anterior lobes, each lobe margined with several sensillae ( Fig. 3 F).

Second antenna. Peduncle setose; exopod and endopod with 11 flagellomeres ( Fig. 3 E); each flagellomere dorsally with 4–6 long distally directed spines and ventral surface with plumose setae ( Fig.5 C).

Carapace. 6.92± 0.71 mm length and 3.94± 0.37 mm height. Oblong ovate in shape, broader anteriorly and tapering posteriorly, dorsal margin straight, ventral margin gently curved, umbone prominent; carapace with 10–15 distinct growth lines ( Fig. 2 A & B); growth lines with sparse setae separated by nearly their length ( Fig. 2 D); interval sculpturing of distinct longitudinal carinae perpendicular to the growth lines in the younger intervals and diminishing distally ( Fig. 2 C); microsculpturing not observed under SEM ( Fig. 4 E).

Thoracopods. 22–24 pairs. Clasper movable finger (endopod) broad basally, tapering and hooked distally; apex with many small scales; large palp (endite V) arcuate, of two palpomeres, palpomere length subequal in both claspers; distal palpomere (endite V outgrowth) slightly elongated, apex with fine setae; small palp (endite IV outgrowth) cylindrical, nearly twice as long as broad, directed anteriorly or slightly posteriorly, with apex covered with fine setae; palm (endite IV) broadly rectangular, projecting slightly obtusely, gripping area covered with small roughly conical, blunt tipped spines, increasing in size posteriorly ( Fig. 4 B); gripping area as long as broad in first clasper, slightly longer than broad in second clasper; clasper 1 endite III roughly triangular, length half the width at base, apex acute; clasper 2 endite III smaller, triangular with blunt apex ( Fig. 4 A & C). Other thoracopods structure as per genus, decreasing in size posteriorly; last 5–8 very small, ( Fig. 3 A & B).

Abdomen. Segments 10–24 dorsal margin each bearing a transverse row of 5–8 aciculate, posteriorly directed setae ( Fig. 4 G).

Telson. Dorsal margin slightly arched, posteriolateral ridges with 25–30 spines in three size and shape classes: (type A), long triangular spines length two to three times longer than basal width, situated just proximal to posteriolateral spiniform projection; (type B), triangular spines length subequal to basal width, anterior most spines slightly recurved, situated along telson ridge, roughly half the size of type A spines; (type C), small triangular spines similar to type B spines in shape, roughly half the size or smaller of the type B spines, situated along the telson ridges; spiniform projection curved dorsally, 0.4 times length of cercopod ( Figs. 4 D & F); caudal filaments originating between the 1st and 2nd spines of telson ridges.

Cercopod. Long, straight, subequal in length to telson dorsal margin; apex bent dorsally, not reaching the posteriolateral projection of telson; dorsal margin medial 80% with longitudinal row of small spinulae, ~ 30–45 in number ( Fig. 4 D; Fig. 5 D).

Female. Carapace 6.74 mm 0.54 mm length and 3.92 mm 0.31 mm breadth. Slightly smaller than male.

Rostrum broadly triangular.

Occipital condyle elongate conical.

Occipital notch wider than in male ( Fig.3 D).

Thoracopods 9 and 10 with long epipodites for carrying eggs ( Fig. 3 B), 2–6 type C spines present between two type B spines ( Fig. 3 G).

Egg. As per the genus, smooth and spherical. Size: ~ 200µm.

Differential diagnosis. This species differs from all other described Indian Leptestheria (sensu Rogers & Padhye, 2015) by having three classes of spines by size and shape on the telson posteriolateral ridges. The other species (such as L. nobilis ( Sars, 1900) and L. sarsi Daday, 1923 ) have spines of similar sizes or the spines are randomly placed and of unequal length. Leptestheria gurneyi sp. nov. most closely resembles the recently described L. kunmingensis Shu et al., 2015 from China, but differs in that L. kunmingensis has two size classes of spines instead of three. The cercopod of L. gurneyi sp. nov. is also straight in both sexes and has similar sized dentition on its dorsal margin, whereas in L. kunmingensis the spinulae bear smaller spinules; the male cercopod has a longitudinal sulcus, and the female cercopod is arcuate. Leptestheria gurneyi sp. nov. lacks the endopodal spine on clasper 1 that is present in L. kunmingensis . Distinct sexual dimorphism in the occipital condyle structure is also a unique character not observed and/or reported from other Indian species ( Sars, 1900; Daday, 1923; Simhachalam & Timms, 2012; Padhye et al. 2015; Shu et al. 2015) (Table 1)

Distribution. Currently known only from its type locality.

Figures

FIGURE 1. Map showing the locality of Leptestheria gurneyi sp. nov. from the Western Ghats of Maharashtra.

FIGURE 2. Leptestheria gurneyi sp. nov. A, carapace. B, dorsal view of carapace. C, carapace (part) showing the longitudinal lines. D, carapace (part) showing the setae on the carapace (Scale bars: A – B: 1 mm. C – D: 0.01 mm).

FIGURE 3. Leptestheria gurneyi sp. nov. A, male 1. B, female. C, male head. D, female head. E, second antenna. F, first antenna. G, female telson (Scale bars: A – B: 1 mm; C – D: 0.2 mm; E, 0.2 mm; F, 0.1 mm; G, 0.5 mm).

FIGURE 4. Leptestheria gurneyi sp. nov. SEMs. A, clasper 1. B, gripping area of the palm (endite IV). C, clasper 2. D, telson showing cercopod (male) (A, B & C represent three types of spines observed). E, carapace (part) surface showing no sculpturing. F, telson margin spines. G, dorsal margin armature (Scale bars: A – B: 1 mm; C – D: 1 mm; E, 0.2 mm; F, 0.1 mm; G, 0.5 mm).

FIGURE 5. Leptestheria gurneyi sp. nov. A, male head showing ocellus. B, female head showing ocellus. C, single flagellomere of second antenna. D, cercopod (female) (Scale bars: A – B: 0. 2 mm; C – D: 0.1 mm).