Caridina sarasinorum Schenkel 1902

(Fig. 3)

Caridina sarasinorum Schenkel, 1902: 492, Pl. 8: Figs. 2a–e, 4a [type locality: Danau Poso, Sulawesi (Celebes), Indonesia]; Bouvier, 1925: 168, Figs. 356–359; Chace, 1997: 19.

Material examined. – Lectotype: ovigerous female, cl 3.1 mm, BMNH 2 a, Lake Poso, central Sulawesi, Indonesia, coll. Sarasin, no date indicated.

Paralectotypes: 4 males, cl 2.6–2.9 mm, 6 females, cl 2.7–3.4 mm, BMNH 2 a, Lake Poso, central Sulawesi, Indonesia, coll. Sarasin, no date indicated.

Other material: 1 male, cl 3.0 mm, ZRC 2007.0471, east coast of Lake Poso at Desa Besuna, Kab. Poso, Sulawesi Tengah, rocky area, coll. C. Schubart et al., 22 Jan.2000; 1 male, cl 2.4 mm, 2 ovigerous females cl 3.0–3.3, egg 0.8 × 0.5 mm, 12 females, cl 2.0– 3.7 mm, MZB CRU-1641, south coast of Lake Poso at Desa Pendolo, Kab. Poso, Sulawesi Tengah, white sand with gravel substrate, Schubart et al., 22 Jan.2000; 15 females, cl 3.8–4.5 mm, ZRC 2007.0472, along Sungai Poso near the outlet of Lake Poso, up to the jetty across Hotel Pamona Indah at the coast of Lake Poso, Tentena, Kab. Poso, Sulawesi Tengah, Indonesia, sandy substrate with clear water, C. Schubart et al., 20 Jan.2000; 2 females, cl 3.8 mm, ZRC 2007.0473, west coast of Lake Poso at Taipa area, Kab. Poso, Sulawesi Tengah, rocky shore with sand substrate, coll. C. Schubart et al., 22 Jan.2000; 19 males, cl 2.2–3.5 mm, 11 females, cl 2.2–3.8 mm, ZRC 2007.0474, Sungai Poso at the outlet of Lake Poso, across the new bridge at rocky cliff, Tentena, Kab. Poso, Sulawesi Tengah, Indonesia, coll. C. Schubart et al., 22 Jan.2000; 2 male, 2.4 mm, 1 female, cl 2.2 mm, ZRC 2007.0475, 0–1 m, Lake Poso at Tentena, mud substrate with coarse gravel, Sulawesi, Indonesia, coll. H. Larson, 6 Sep.1989.

Comparative material examined. – Two syntypes of C. simoni Bouvier, 1904, cl 4.0– 4.1 mm, MNHN-Na 856, Ceylon (Sri Lanka), freshwater, coll. E. Simon, no date indicated.

Description. – Rostrum reaching near to or slightly beyond end of scaphocerite, upturn anteriorlly, armed dorsally with 12–19 teeth on posterior 1/2–3/4, including 3–7 on carapace posterior to orbital margin, armed ventrally with 8–17 teeth. Antennal spine placed lower than inferior orbital angle. Pterygostomian margin broadly rounded.

Sixth abdominal segment 0.6–0.7 times as long as carapace, shorter than telson, twice as long as fifth segment. Preanal carina with a spine. Telson 4.1 times as long as wide, not terminating in a projection, with 3–5 pairs of dorsal spinules on distal half of telson, with 3 or 4 pairs of distal spines, lateral pair longer than intermediates. Preanal carina with a spine.

Eyes well developed, anterior end reaching to 0.8 times length of basal segment of antennular peduncle. Antennular peduncle as long as carapace; basal segment of antennular peduncle as long as combined length of second and third segment, anterolateral angle pointed, reaching half length of the second segment, second segment about twice as long as third segment. Stylocerite reaching to 0.9 times length of basal segment of antennular peduncle or end of this segment. Scaphocerite 4.4 times as long as wide.

Incisor process of mandible ending in irregular teeth, molar process truncated. Lower lacinia of maxillula broadly rounded, upper lacinia elongated, with a number of distinct teeth on inner margin, palp slender. Upper endites of maxilla subdivided, palp slender and elongated, scaphognathite tapering posteriorly with numerous long, curved setae at posterior end. Palp of first maxilliped broad. Podobranch of second maxilliped reduced to a lamina. Third maxilliped reaching to end of second segment of antennular peduncle, with ultimate segment slightly shorter than penultimate segment.

Epipods well developed on first pereiopod, greatly reduced or absent on second pereiopod, totally absent on third to fifth pereiopods. First pereiopod reaching to end of basal segment of antennular peduncle, merus 2.0–2.7 times as long as wide, shorter than carpus; carpus slightly excavated anteriorly, 1.8–2.7 times as long as high, shorter than chela; chela 2.0–2.7 times as long as broad, fingers subequal to palm in length. Second pereiopod reaching to end of second segment of antennular peduncle, merus 3.2–4.6 times as long as wide, shorter than carpus; carpus 5.0–6.0 times as long as high, 1.3–1.5 times as long as chela; chela 2.8–3.0 times as long as broad, fingers 1.2–1.4 times as long as palm. Third pereiopod reaching to end of antennular peduncle; propodus 10–11 times as long as wide, 3.3–4.4 times as long as dactylus; dactylus 3.0 times as long as wide (spines included), with 5–7 spines on flexor margin. Fifth pereiopod reaching beyond end of basal segment of antennular peduncle; propodus 12 times as long as wide, 3.2–3.5 times as long as dactylus; dactylus 3.0–3.9 times as long as broad, with 48–50 spinules on flexor margin.

Endopod of male first pleopod sub-rectangular, 0.25 times length of exopod, without appendix interna. Appendix masculina of male second pleopod short, reaching to half length of endopod, appendix interna stout, about half length of appendix masculina.

Uropodal diaeresis with 8–11 movable spinules.

Eggs 0.85 × 0.5 mm.

Habitat. – This species is commonly found in Lake Poso and prefers rocky shores and sandy substrates.

Remarks. – With regard to the form of the rostrum, C. sarasinorum is most similar to C. simoni Bouvier, 1904 from Sri Lanka. It can be distinguished from C. simoni by the absence of an appendix interna on the endopod of the male first pleopod and the presence of a preanal spine (based on comparative material examined).

Distribution. – Endemic to Lake Poso in central Sulawesi, Indonesia.