Streptocephalus simplex Bond, 1943

Velu, Chinavenmeni S & Munuswamy, Natesan, 2005, Updated diagnoses for the Indian species of Streptocephalus (Crustacea: Branchiopoda: Anostraca), Zootaxa 1049, pp. 33-48 : 37-39

Streptocephalus simplex Bond, 1943

Material examined. Specimens were collected from Marathwada (19°53N, 75°23E) and Ranchi (23°23N, 85°23E). Accession numbers are NM/FS/121 and 122, respectively.

Measurements: 20 males (24.3–27.6 mm); 3 females (21.1–25.1 mm).

Description: Male Proximal segment of second antennae is sub­cylindrical, rolled up ventrally, and the terminal part of antennae is hidden between the distal ends ( Fig. 2 A). Four anterolateral subcrenulate papillae on the proximal segment of second antennae. The proximal being the largest ( Fig. 2 B). Peduncle bears lateral row of slender spines at the distal curve ( Fig. 2 C). Elongate, cheliform “hand”; “thumb” is half length of “finger” bearing an arcuate spur and an anterior “shoulder” opposite the spur. Finger is as long as peduncle and spinose, anteriorly with spines arranged as curved strong spines. At distal bend in anterior ramus of the finger the longitudinal row of spines turns to the medial surface of the ramus and ends on the posterior surface ( Fig. 2 D). Posterior ramus is curved and smooth. Thoracic and abdominal segments are smooth. Bases of proximal portion of penes each with lateral linguiform projections. Proximal non­retractile part of penis bears an anteriorly curved median projection with five spines on the anterior surface ( Fig. 2 E). Eversible portion of penes has two rows of flat, acute spines observed on the entire length of the penis ( Fig. 2 F). Cercopod are lanceolate, narrow, fringed to tip with plumose setae.

Female. Second antennae are flat, oval in shape ( Figs. 2 G, H). Brood­pouch extends to fifth abdominal segment ( Fig. 2 I). An orange streak is observed on the ventral side of the brood pouch as in S. dichotomus .

Cyst. The cyst surface is covered with an irregular structure and narrow depressed fields ( Figs. 2 J, K). The ridges are raised, centered fields broad and narrow with pores on their surface.

Remarks. Streptocephalus simplex Bond, 1934 can be distinguished from other species on the basis of the male second antennae, which have strong, curved spines on the posterior ramus; the thumb is shorter than the finger. Also unique is that the cyst surface has narrow depressed fields.

Figures

FIGURE 2. Streptocephalus simplex BOND. A. Male, lateral view of head. B. Fleshy process on the second antennae. C. Male antennae, lateral view. D. Medial view of male antenane. E. Ventral view of male genital region, arrow showing the spines on the protuberances. F. Distal part of protracted penis showing spines on their surface. G. Female, ventral view of head. H. Single antennae (upper view). I. Lateral view of female abdomen and brood­pouch. J. Cyst. K. Details of cyst showing ridges, depression and pores.