AnimaliaDecapodaPalaemonidaeMantelattoFernando L.PileggiLeonardo G.PantaleãoJoão A. F.MagalhãesCélioVillalobosJosé LuisÁlvarezFernandoMultigene phylogeny and taxonomic revision of American shrimps of the genus Cryphiops Dana, 1852 (Decapoda, Palaemonidae) implies a proposal for reversal of precedence with Macrobrachium Spence Bate, 1868Zookeys0172021104715519810.3897/zookeys.1047.66933CD580649-0B79-5C4C-A81D-7FDE955D1687 Macrobrachium luscus (Holthuis, 1973)comb. nov. Bythinops luscusSbordoni, Argano & Zullini, 1973: 24 (nomen nudum). Bithynops luscusHolthuis, 1973: 136, figs 1, 2. – Holthuis 1977: 181. – Hobbs, Hobbs and Daniel 1977: 25 (key), 46, fig. 17. – Reddell 1981: 108, fig. 15 (map), 319 (in list), 323 (list). – Villalobos 1982: 217 (in list). – Fitzpatrick 1983: 217. – Holthuis 1986: 606 (list). – Holthuis 1993: 103, fig. 89. – Hobbs III 1993: 20 (list). – Álvarez et al. 1996: 110, chart 12.2 (list). – Pereira 1997: 47, table 6 (list). – Fransen et al. 1997: 15 (catalog). – Jayachandran 2001: 17, fig. 1. – Palacios-Vargas 2006: 7 (list). – Mejía-Ortiz et al. 2013: 32, table 1. – Lamoreux et al. 2015: 306, Appendix 2 (list). – De Grave et al. 2015b: 7, table 3. Cryphiops (Bithynops) luscus. – Villalobos Hiriart et al. 1989: 163, figs 1, 6a, c, 8a. – Villalobos-Hiriart et al. 1993: 281, table 5 (list). – Hobbs III 1994: 98 (list). – Fransen et al. 2010: 30, Appendix III (list). – De Grave and Fransen 2011: 316 (catalog). – Álvarez et al. 2011: 258, fig. 4a. – Palacios-Vargas and Reddell 2013: 43 (list). – Palacios-Vargas et al. 2014–2015: 22. – Quiroz-Martínez et al. 2014: table S1 (list). – Alvarez and Villalobos 2016: 250, table 8.1 (list). Cryphiops luscus. – Palacios-Vargas 2006: 7 (list). – Baldari et al. 2010: 48, fig. 1 (map), 52, table 1. – Botello and Alvarez 2013: table 1 (list). – Mantelatto et al. 2020: 915 (key).Material examined.

Mexico – Chiapas • 8 males, tl 30.5–49.4 mm, 15 ovigerous females, tl 30.8–46.3 mm; Municipality of La Trinitaria, Rancho de San Rafael del Arco, Gruta del Arco; 07 Apr. 1986; J.L. Villalobos leg.; CNCR 5759.

Description.

Rostrum. Short, directed slightly downwards, tip directed slightly upwards, reaching or slightly overreaching joint between second and third article of antennular peduncle, and at level of distal third of scaphocerite; upper margin convex over orbit, with 5–8 teeth regularly spaced, first over or slightly behind posterior edge of orbit; lower margin with none or one tooth.

Cephalon. Scaphocerite 2.5 × as long as wide; outer margin straight.

Carapace. Smooth, with minute punctuations; antennal spine small, slightly overreaching lower portion of orbit; hepatic spine absent. Lower orbital angle obtuse, moderately pronounced.

Pereiopods.P1 slender, reaching with nearly entire chelae beyond scaphocerite; fingers slightly longer than palm; chelae 2/3 length of carpus. P2 moderately robust, with several spines, equal in form and size, reaching with proximal third of carpus beyond scaphocerite; ischium evidently shorter than merus; merus as long as carpus; carpus as long as palm, with basal constriction; propodus 2 × as long as dactylus, 2 × as long as carpus; palm inflated, nearly 3 × as long as high; fingers as long as palm, with numerous small spinules; cutting edge with two denticles of same size in both teeth. P3–P5 with all joints covered with row of small spinules on the lower margin; P3 reaching with entire dactylus beyond scaphocerite, propodus 2 × as long as dactylus, propodus slightly longer than merus; P4 reaching with tip of dactylus end of scaphocerite, propodus 3 × as long as dactylus, propodus slightly longer than merus; P5 reaching with tip of dactylus half-length of scaphocerite, propodus 3 × as long as dactylus, propodus slightly longer than merus.

Pleon. Smooth. Somite 5 with posteroventral angle of pleuron acute; somite 6 nearly 2 × as long as somite 5. Inter-uropodal sclerite without, keel-shaped pre-anal carinae.

Pleopods.PL2 with appendix masculina 2 × as long as appendix interna.

Uropods. Exopodite with mobile spines as long as spiniform projection of outer margin.

Telson. Broad, smooth, slightly longer than abdominal somite 6, bearing two pairs of dorsal spinules closer to posterior margin of telson. Posterior margin ending in moderately acute triangular point, with several plumose setae and two pairs of posterior spinules, inner pair overreaching end of telson.

Size.

See in material examined.

Color.

Whitish to transparent.

Type locality.

México, Chiapas, Municipality of La Trinitaria, Gruta del Arco, El Rancho de San Rafael Del Arco, Lagunas de Montebello, altitude 1,470 m. Recent visits to the type locality showed an increasing contamination in the lakes that supply water to the underground stream of the Gruta del Arco, and the collections of specimens were not successful, at least in the closest access to the water pools. Possibly, M. luscus comb. nov. is seriously threatened.

Distribution.

Only known from the type locality (Holthuis 1973; present paper).

Life cycle.

This is a cave species exclusive of inland waters, therefore independent of brackish to complete its life cycle. The eggs are few and large: 1.8–2.4 mm (Villalobos Hiriart et al. 1989). The duration of the embryonic development is probably long and with few larval stages following the pattern of other inland species.

Remarks.

This species is similar to Macrobrachium valdonii nom. nov., comb. nov., which is the other hypogean species with abbreviated development and without hepatic spine. The most remarkable differences between them concerns the length of the rostrum, and the proportion of the articles of second pereiopod (Table 2). In M. luscus comb. nov., the rostrum is short, reaching or slightly overreaching joint between second and third article of antennular peduncle, and at level of distal third of scaphocerite. The ischium of the second pereiopod is evidently shorter than the merus, and the dactyl is little longer or as long as palm. In M. valdonii nom. nov., comb. nov., the rostrum is longer, reaching the third article of antennular peduncle and the distal border of scaphocerite; the ischium of the second pereiopod is slightly shorter than the merus, and the dactyl is slightly shorter than the palm.

Morphological comparison of key characters for the species previously included in the genus Cryphiops Dana, 1852.

M. alevillalobosi nom. nov., comb. nov.M. caementarius (Molina, 1782), comb. nov.M. candango nom. nov., comb. nov.M. luscus (Holthuis, 1973), comb. nov.M. perspicax (Holthuis, 1977), comb. nov.M. valdonii nom. nov., comb. nov.
Rostrum Reaching slightly beyond first third of ultimate article of antennular peduncle, and at level of distal fourth of scaphocerite. Upper margin with 6–9 teeth regularly spaced, first one behind of posterior edge of orbit; lower margin with 1–3 teethReaching or slightly beyond the first article of antennular peduncle, and at level of proximal third of scaphocerite. Upper margin with 6–8 teeth regularly spaced, first one or two behind of posterior edge of orbit; lower margin with 0–4 teethReaching end of antennular peduncle, and little before the distal margin of scaphocerite. Upper margin convex over orbit, with 7 teeth, first and sometimes the second, slightly behind posterior edge of orbit; lower margin with 1 toothReaching or slightly overreaching joint between second and third article of antennular peduncle, and at level of distal third of scaphocerite. Upper margin convex over orbit, with 5–8 teeth regularly spaced, first over or slightly behind posterior edge of orbit; lower margin with 0–1 toothReaching joint between second and third articles of antennular peduncle, and at level of distal third of scaphocerite. Upper margin with 5–8 teeth regularly spaced, first one at level or slithy behind posterior edge of orbit; lower margin with 1 or 2, rarely 3 teethAlmost reaching the third article of antennular peduncle, and before the distal border of scaphocerite. Upper margin with 8 teeth, lack teeth in postorbital position and on ventral margin
Eyes Cornea normal and larger than the peduncleCornea normal and larger than the peduncleCornea normal and larger than the peduncleCornea reduced, smaller than the peduncleCornea normal and larger than the peduncleCornea with a small apical black point, smaller than the peduncle
Scaphocerite 2.6 × as long as wide2 × as long as wide2.5 × as long as wide2.5 × as long as wide (Holthuis, 1973)2.6 × as long as wide2.4 × as long as wide
Lower orbital angle Rounded, moderately pronouncedRounded, pronounced, as long as antennal spineSubacute, strongly pronouncedObtuse, moderately pronouncedSubacute, moderately pronouncedSubacute, moderately pronounced
Antennal spine In the middle of the lower orbital angleLittle below the lower orbital angleLittle below the lower orbital angleLittle below the lower orbital angleLittle below the lower orbital angleBelow the lower orbital angle
First male pereiopod Reaching with distal third of carpus beyond scaphoceriteReaching with the larger part of the carpus beyond scaphoceriteReaching with almost half length of carpus beyond scaphoceriteReaching with nearly entire chelae beyond scaphoceriteReaching with nearly entire chelae or small part of carpus beyond scaphoceriteReaching with the palm beyond scaphocerite
Second male pereiopod Equal in form and size, reaching with distal third of merus beyond scaphocerite; ischium 0.75× length of merus; merus as long as carpus; carpus as long as palm, with slight basal constriction; propodus 2.5× as long as dactylus, and 1.6× as long as carpus; palm compressed, nearly 5× as long as high; fingers 0.62× length of palmDifferent in form and size. Largest reaching with half of merus beyond scaphocerite; ischium, merus and carpus are covered with spinules, smaller than those of the chela; ischium more than 0.5× length of merus; merus longer than carpus; carpus slightly less 0.5× length of palm, with strong basal constriction; propodus 2.5× as long as dactylus, and 3.3× as long as carpus; palm compressed, nearly 2.3× as long as high; fingers 0.75× length of palm, little gapingSimilar in shape, different in size. Largest, reaching with distal portion of merus beyond scaphocerite; ischium nearly as long as merus; merus as long as carpus; carpus slightly shorter than palm; propodus 2.5× the length of dactylus, 2× as long as carpus; palm inflated, less than 3× as long as high; fingers 0.71× the lenght of palmEqual in form and size, reaching with proximal third of carpus beyond scaphocerite; ischium evidently shorter than merus; merus as long as carpus; carpus as long as palm, with moderate basal constriction; propodus 2× as long as dactylus, 2× as long as carpus; palm inflated, less than 3× as long as high; fingers little longer or as long as palmEqual in form and size, reaching with proximal third of carpus beyond scaphocerite; ischium slightly shorter than merus; merus as long as carpus; carpus as long as palm, with a moderate basal constriction; propodus 2.2× as long as dactylus, 2× as long as carpus; palm inflated, 3× as long as high; fingers slightly shorter (0.8) than palmSubequal in size, reaching with half of carpus beyond scaphocerite; ischium 0.9× merus; carpus 0.8× as long as merus and 0.85× palm length; propodus 1.5× as long as dactylus, 2.5× as long as carpus; palm 3.3× as long as high and 0.8× of dactylus length
Appendix masculina Almost as long than endopod of second pleopod. Setae thick and shortLittle longer than half endopod length of second pleopod. Setae thick and shortShorter than endopod of second pleopod.Shorter than endopod of second pleopod. Setae thick and shortShorter than endopod of second pleopod. Setae slender and longShorter than endopod of second pleopod
Inter-uropodial sclerite Without keel-shaped pre-anal carinaeWith strong, keel-shaped pre-anal carinaeWithout keel-shaped pre-anal carinaeWithout keel-shaped pre-anal carinaeWithout keel-shaped pre-anal carinae
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