Caridina enbilului, Klotz & von Rintelen & Christodoulou, 2019

Klotz, Werner, von Rintelen, Thomas & Christodoulou, Magdalini, 2019, Middle East Caridina (Decapoda: Atyidae): Redescription of C. fossarum Heller, 1862, description of three new species, and remarks on the status of C. syriaca Bouvier, 1904 and C. babaulti basrensis Al-Adhub & Hamzah, 1987, Zoologischer Anzeiger 283, pp. 161-185 : 171-175

Caridina enbilului sp. nov.

( Figs. 8 – 10)

Material examined

Holotype. ♀ cl 3.6 mm, Syria, Hassaka, Ain Saluba and Ain Hamza in Ras al Ain , 36 ° 51 ' N 40 ° 4 ' E, leg. F. Krupp, 03.10.1988, SMF-51548 .

Paratypes. 17 ovig. ♀♀ cl 4.0 – 5.1 mm, 10 ♀♀ cl 3.6 – 4.7 mm, 8 ♂♂ cl 2.8 – 3.6 mm, same data as holotype, SMF-43903 ; 8 ♀♀ cl 2.4 – 5.0 mm, 1 ♂ cl 2.5 mm, Syria, Hasakah, river in Ain Kibrit near Quattina , leg. F. Krupp, 05.10.1988, SMF-43902 .

Description

Cephalothorax and cephalic appendages. Medium-sized shrimp with carapace length 3.1 – 5.1 mm in apparently adult specimens (n = 45). Carapace ( Fig. 8 A ) smooth, antennal spine at inferior orbital angle, pterygostomial angle rounded, with a distinct tooth. Rostrum ( Fig. 8 A ) strong, slightly to distinct sigmoid, armed with 23 – 33 teeth throughout dorsal margin, with 6 – 14 teeth in distal half of ventral margin, reaching to or slightly beyond distal margin of scaphocerite in most specimens, in some specimens reaching almost to distal end of the antennular peduncle, 0.78 – 1.19 (median 0.96, n = 14) times as long as carapace. Rostrum formula 2 – 4 + 19 – 30/6 – 14. Eyes ( Fig. 8 A ) well developed with pigmented cornea globular. Antennula and antenna well developed. Antennular peduncle ( Fig. 8 B ) 0.70 – 0.96 (median 0.80, n = 9) times as long as carapace, first segment 1.90 – 2.50 (median 2.33, n = 8) times as long as second segment, distolateral angle with an acute projection 0.50 – 0.73 (median 0.65, n = 8) times as long as second segment; second segment 1.60 – 1.88 (median 1.76, n = 8) times length of third segment. Stylocerite pointed, reaching to 0.84 – 1.0 (median 0.93, n = 8) times of basal segment of antennular peduncle. Scaphocerite ( Fig. 8 C ) with well-developed distolateral tooth, 3.64 – 4.15 (median 3.84, n = 4) times as long as wide.

Abdominal somites, telson and uropods. Sixth abdominal somite 0.54 – 0.67 (median 0.60, n = 7) times length of carapace, 1.58 – 1.89 (median 1.74, n = 7) times as long as fifth somite, 0.79 – 0.94 (median 0.87, n = 7) times as long as telson. Telson ( Fig. 8 D, I ) slightly tapering distally, distal convex without a median projection, lateral angles not overreaching distal margin, dorsal with 3 – 6 (n = 6) pairs of short spiniform setae and one pair of short spiniform setae dorsolateral; distal margin with 6 – 9 (n = 6) strong spiniform setae. Lateral pair longer than intermediate ones, sublateral pair shortest. Preanal carina ( Fig. 8 E ) low, rounded, without a tooth or spine. Uropodal diaeresis ( Fig. 8 F ) with 10 – 14 (n = 7) movable spiniform setae, outermost one shorter than lateral angle.

Mouthparts and branchiae. Mandible ( Fig. 9 A ) without palp, incisor process ending in irregular teeth, molar process truncated. Lower lacinia of maxillula ( Fig. 9 B ) broadly rounded to subrectangular with long pappose setae and few rows of serrate setae near margin, upper lacinia elongate, with numerous distinct cuspidate setae flanked by a row of serrate setae on inner margin and few pappose setae subterminal, palp slender with few pappose setae and one cuspidate seta near tip. Upper endites of maxilla ( Fig. 9 C ) subdivided, furnished with numerous pappose, simple and papposerrate setae arranged in rows, palp slender, scaphognathite tapering posteriorly, fringed with long, curved serrulate setae at truncated posterior margin and plumose setae inferior. Palp of first maxilliped ( Fig. 9 D ) ending in a short, triangular extension, caridean lobe and flagellum with plumose setae, basis with numerous pappose, papposerrate and serrate setae arranged in rows and tufts. Endopod reaching beyond distal margin of caridean lobe. Podobranch on second maxilliped ( Fig. 9 E ) well developed, exopod slender, overreaching propodal segment, with long plumose setae distally; basis and merus with rows of pappose setae, distolateral margin of penultimate segment with several pappose and serrate setae; dactylus with numerous serrate setae flanked by a row of pappose setae. Third maxilliped ( Fig. 9 F ) slender, with one well developed and one small arthrobranch; exopod slender, slightly overreaching the distal margin of antepenultimate segment, with few long plumose setae distally; antepenultimate segment of endopod slender, with some pappose setae basally, distal with few short simple setae; penultimate segment slender, with straight lateral margins, with few plumose setae on dorsal and ventral margin, inner margin with rows of short serrated setae; ultimate segment about as long as penultimate segment, tapering distally, ending in a claw-like curved spiniform setae (nail), proximal to the nail 4 – 7 cuspidate setae; inner margin dense beset with rows of serrate setae, some serrate setae also on dorsal margin; epipod well developed, with distal hook. Podobranch on second maxilliped well developed, two arthrobranchs (one of them small) on third maxilliped, first pereiopod with a small but well developed arthrobranch. Pleurobranchs present on all pereiopods. Well-developed epipods (with hooks on distal end) present on third maxilliped and first four pereiopods. Setobranchs on all pereiopods.

Pereiopods. First and second pereiopods chelate. Chela of first pereiopod ( Fig. 8 G ) caridinoid in shape, with well-developed palm, 1.89 – 2.43 (median 2.14, n = 8) times as long as wide, 1.24 – 1.34 (median 1.30, n = 8) times as long as carpus; tips of fingers rounded, with tufts of setae distally; dactylus 3.0 – 4.0 (median 3.42, n = 8) times as long as wide, 1.07 – 1.8 (median 1.36, n = 8) times as long as palm; carpus slender, slightly excavated distally, 1.91 – 2.45 (median 2.23, n = 8) times as long as wide, 0.81 – 0.89 (median 0.87, n = 6) times as long as merus. Merus not inflated, 2.91 – 3.65 (median 3.31, n = 6) times as long as wide, 1.16 – 1.30 (median 1.25, n = 6) as long as ischium. Chela of second pereiopod ( Fig. 8 H ) caridinoid in shape, with well-developed palm, 2.5 – 2.89 (median 2.81, n = 6) times as long as wide, 0.65 – 0.83 (median 0.78, n = 6) times as long as carpus; tips of fingers rounded, with tufts of setae distally, dactylus 3.5 – 4.80 (median 4.08, n = 6) times as long as wide, 1.33 – 1.60 (median 1.39, n = 6) times as long as palm; carpus slender, 4.78 – 6.32 (median 5.30, n = 6) times as long as wide, 1.04 – 1.28 (median 1.09, n = 6) times as long as merus. Merus not inflated, 4.29 – 6.43 (median 5.41, n = 6) times as long as wide, 1.17 – 1.68 (median 1.25, n = 6) times as long as ischium. Third pereiopod ( Fig. 10 A ) slightly dimorph between sexes; dactylus ( Fig. 10 B ) 2.14 – 2.50 (median 2.50, n = 3) times as long as wide (terminal claw and spiniform setae on flexor margin included), terminating in a large claw, with 5 or 6 accessory curved spiniform setae on flexor margin in males, 3.5 – 3.83 (n = 2) times as long as wide (terminal claw and spiniform setae on flexor margin included) terminating in one large claw with 6 or 7 accessory straight spiniform setae on flexor margin in females; propodus not dilated distally and with two rows of small spiniform setae on inner margin ( Fig.10 G ), propodus 8.36 – 11.0 (median 9.43, n = 5) times as long as wide, 3.29 – 3.86 (median 3.33, n = 5) times as long as dactylus; carpus 4.33 – 5.5 (median 5.17, n = 6) times as long as wide, 0.56 – 0.72 (median 0.65, n = 5) times as long as propodus, 0.43 – 0.59 (median 0.51, n = 6) times as long as merus, with one large spiniform seta near distal margin and 3 or 4 small spiniform setae on inferior margin; merus 6.0 – 8.64 (median 6.76, n = 6) times as long as wide, 1.71 – 2.31 (median 1.97, n = 6) times as long as carpus, bearing 3 or 4 strong movable spiniform setae on externo-inferior margin; ischium with one spiniform seta. Fourth pereipopod similar to third but slightly smaller ( Fig. 10 C – D). Fifth pereiopod ( Fig. 10 E ) slender; dactylus ( Fig.10 F ) 3.33 – 4.29 (median 3.85, n = 6) times as long as wide (terminal claw and spiniform setae on flexor margin included), terminating in one large claw, with 30 – 40 spiniform setae on flexor margin; propodus with 2 rows of small spiniform setae on ventral margin, distal pair of spiniform setae not enlarged, propodus 9.43 – 12.25 (median 9.95, n = 6) times as long as wide, 2.83 – 3.3 (median 3.21, n = 6) times as long as dactylus; carpus 2.79 – 5.30 (median 4.92, n = 6) times as long as wide, 0.51 – 0.57 (n = 6) times as long as propodus, 0.58 – 0.67 (median 0.63, n = 6) times as long as merus, with 1 strong spiniform setae near distal margin and 3 – 5 small spiniform setae on inferior margin; merus 6.67 – 8.50 (median 7.32, n = 6) times as long as wide, 1.49 – 1.71 (median 1.6, n = 2) times as long as carpus, bearing 2 or 3 strong movable spiniform setae on externo-inferior margin. Ischium without a spiniform seta.

Pleopods. Endopod of male's first pleopod ( Fig. 10 H ) slender subrectangular, without an appendix interna, 2.77 – 3.67 (n = 2) times as long as proximal width, 0.43 times as long as exopod, with simple setae on inner margin, with pappose setae on distal and outer margin. Appendix masculina on male second pleopod ( Fig. 10 I ) rod-like, 9.0 – 11.33 (median 10.0, n = 3) times as long as wide, 0.65 – 0.82 (median 0.68, n = 3) times as long as endopod, armed with strong spiniform setae on inner and distal margin; appendix interna arising from about 0.4 times length of appendix masculina, reaching to about 0.6 times length of appendix masculina.

Sexual dimorphism. Males similar to females except size, third and fourth pereiopods and sexual appendages. The main morphological differences from females lead in the shape and spinulation of dactyli of third and fourth pereiopods ( Fig. 10 A – D, G) and structure of the endopod of first pleopod as well as the presence of an appendix masculina in second pleopod ( Fig. 10 H – I).

Reproductive biology. Ovigerous females with few large eggs; size of undeveloped eggs (without eyes) 0.83 – 0.86 × 0.50 – 0.58 mm.

Size. Postorbital carapace length of apparently adult specimens 2.4 – 5.0 mm.

Colouration. Unknown.

Etymology. C. enbilului sp. nov. is named after Enbilulu, the god of rivers and canals in Mesopotamian mythology.

Distribution. C. enbilului sp. nov. is known from two localities at a small river in the north-eastern part of Syria ( Fig. 1 B ).

Remarks. With its strong rostrum armed along the entire dorsal margin, the shape of the male's sexual appendages and a weak sexual dimorphism of the third and fourth pereiopods, C. enbilului sp. nov. resembles C. shahrazadae sp. nov. from Iran, but can be distinguished by the longer rostrum (rostrum 0.9 – 1.2 times as long as carapace vs. 0.4 – 0.8 times in C. shahrazadae sp. nov.), the longer antennular peduncle (0.8 – 1.2 times as long as carapace vs. 0.4 – 0.7 times), a longer tooth at the distal margin of the basal segment of the antennular peduncle (0.50 – 0.73 times as long as second segment vs. 0.38 – 0.55 times as long), and by showing a distinct tooth at the pterygostomial margin of the carapace. The chelae of the Syrian species are shorter in relation to the proximal segments (chela of first pereiopod 1.2 – 1.3 times as long as carpus vs. 1.4 – 1.7 times in C. shahrazadae sp. nov., 1.1 times as longs as merus vs. 1.2 – 1.4 times, chela of second pereiopod 0.7 – 0.8 times as long as carpus vs. 0.9 times in C. shahrazadae sp. nov.). The arthrobranch on the first pereiopod is well developed vs. reduced to a worm-like structure, the podobranch on the second maxilliped is well developed vs. reduced to a lamina with few short protuberances distally and a more slender endopod of the male's first pleopod (2.8 – 3.7 times as long as wide vs. 2.0 times as long as wide in C. shahrazadae sp. nov.). A tooth at the pterygostomial margin is frequently seen in species allied to C. babaulti from India ( Bouvier 1918; Jalihal et al. 1984, Klotz, personal observation). C. enbilului sp. nov. is distinct from C. babaulti by its much stronger and longer rostrum reaching to or slightly overreaching the distal margin of the carapace vs. not overreaching the antennular peduncle in C. babaulti . Further, the endopod of the male's first pleopods is lacking an appendix interna vs. with a distinct appendix interna in C. babaulti .

Figures

Fig. 8. Caridina enbilului sp.nov., female, SMF-43902: A, cephalothorax and cephalic appendages; B, antennula; C,antenna; D, telson; E, preanal carina; F,uropodal diaeresis; G, first pereiopod; H, second pereiopod; I, terminal part of telson. Scale bars indicates 1 mm (A̅E, G̅H) and 0.5 mm (F, I).

Fig. 9. Caridina enbilului sp. nov., female, SMF-43902: A, mandible B, maxillula; C, maxilla; D, first maxilliped; E, second maxilliped; F, third maxilliped. Scale bars indicates 0.5 mm.

Fig.10. Caridina enbilului sp. nov., female, SMF-43902: A, third pereiopod; B, dactylus of third pereiopod; C, fourth pereiopod; D, dactylus of fourth pereiopod; E, fifth pereiopod; F, dactylus of fifth pereiopod. Male, SMF-43902: G, propodus and dactylus of third pereiopod; H, first pleopod. Male, SMF-43902:I, second pleopod.Scale bars indicates 1 mm (A, C,D, G) and 0.5 mm (B, D, F, H, I).

Fig. 1. A, Origin of sequenced specimens (for details see Table 1); B, Map showing the geographic distribution of Caridina species in the Middle East.