Parastacus defossus Faxon, 1898

Ribeiro, Felipe Bezerra & Araujo, Paula Beatriz, 2024, Taxonomic review of the genus Parastacus Huxley, 1879 (Decapoda: Astacidea: Parastacidae) with description of five new species, Zootaxa 5455 (1), pp. 1-84 : 26

Parastacus defossus Faxon, 1898

( Fig. 13–14 )

Parastacus defossus Faxon, 1898: 686 , pl. 67: figs. 3, 4. — Ortmann 1902: 293.—­ Riek 1971: 134.—­ Buckup and Rossi 1980: 677.—­ Hobbs 1989: 79, fig. 370; 1991: 801, fig. 3f. —­ Crandall & De Grave 2017: 641.—­ Rogers et al. 2020: 879 (key), fig. 23.68A.—­ Huber et al. 2022: 276 (key).—­ De los Ríos-Escalante et al. 2022: 1129 (appendix), fig. 1e.—­ Huber et al. 2024: 14 (key).

Type Locality. Montevideo ( Uruguay) .

Type material re-examined. Holotype, ♂, Uruguay, Montevideo, mouth of La Plata, coll. W. E. Safford, U. S S. “Vandalia” ( USNM 19647 ) [Photos examined].

Material examined. Uruguay —­ one male, 1897, coll. Rodrigues (MACN–In 4970–2) ; two males, Maldonado, Ruta 13, km 180, coll. I. Larossa (FC–UDELAR w/n) .

Diagnosis and description. Faxon (1898).

Remarks. Additional morphological characters not mentioned in previous descriptions include: eyes small ( Fig. 13A, B, C ); front narrow ( Fig. 13 , B); epistome anterolateral section with an inconspicuous conical projection ( Fig. 14A ); antennal scale lateral margin straight ( Fig. 14D ); antennule internal ventral border of basal article unarmed ( Fig. 14A ); mandible with cephalic molar process molariform and caudal molar process bicuspidate, incisor lobe with nine teeth; the second and third teeth from the anterior are the largest ( Fig. 14E ); SLP4 very close to each other, medial keel present and not inflated; SLP5 smallest and close to each other, median keel present and not inflated; SLP6 larger than SLP4 and SLP5 with slightly concave dorsal surface, medial keel present and inflated; SLP7 largest and with slightly concave surface, median keel present and slightly inflated; SLP8 smaller than SLP 7, median keel absent, vertical arms of paired sternopleural bridges close to each other, bullar lobes visible and close to each other ( Fig. 14B, C ); male cuticle partition present. This species is morphologically similar to P. pugnax and P. caeruleodactylus in having globose chelipeds, post orbital carinae weakly prominent, telson subrectangular and triangular rostrum, but it is distinguishable in having shorter dactylus and carpus with one blunt spine near the distal end.

Distribution. Uruguay: provinces of Montevideo and Maldonado ( Faxon, 1898). This species was recorded in Brazil, without a detailed locality, for the first time by Ortmann (1902). In the review of Buckup & Rossi (1980), they consider that this species occurs in the state of Rio Grande do Sul, Brazil. The authors redescribed the species based on Brazilian specimens. However, the analysis of photos of the type material of P. defossus and additional material from FC-UDELAR and all Brazilian material previously identified as P. defossus , allowed us to raise the hypothesis that this species does not occur in Brazil. The Brazilian populations probably are composed of cryptic species that need further investigations using molecular tools and are not included here.

Color of live specimens. Not available.

Habitat and Ecology. Burrows ( Faxon, 1898). More data not available.

Figures

FIGURE 13. Parastacus defossus Faxon 1898 (FC-UDELAR w/n): A—­ habitus, dorsal view; B—­ cephalon, dorsal view; C—­ cephalon, lateral view; D—­ first to third male pleonal pleura; E—­ tailfan. Scale bars: A, C, D, E—­ 10 mm; B, F, G—­ 5 mm.

FIGURE 14. Parastacus defossus Faxon 1898 (FC-UDELAR w/n): A—­ epistome; B—­ thoracic sternites and gonopores; C—­ thoracomere 8, caudal view; D—­ antennal scale, lateral view; E—­ mandible; F—­ third maxilliped, ventral view; G—­ third maxilliped, dorsal view; H—­ first pereiopod, lateral view; I—­ first pereiopod, dorsal view; J—­ second pereiopod, lateral view. Scale bars: A, I—­ 3.33 mm; B, C, F, G, H, J—­ 5 mm; D, E—­ 2.5 mm.