Bioacoustics of Hartnollius

DIAGNOSIS Carapace ( Figs 1E ; 14A, B ) Carapace broader than long, flat, with hepatic, subhepatic and branchial regions not markedly inflated, widest part of carapace being more or less in line with antero-lateral angles of mesogastric region. Fronto-orbital distance about half of maximum carapace width in adults. Dorsal surface with shallow grooves: cervical groove terminating anteriorly in a pit near orbital angle; median (or urogastric) groove well-defined but shallow; longitudinal mesogastric groove well-defined but shallow, rising towards frontal margin. Fronto-orbital border half or less than half width of carapace. Front short, narrow, produced and deflexed, with straight lateral margins and upturned lower margin. Mesial lobe of infraorbital margin angular, just joining front edge, completely exposed ( Hartnollius lateralis , see Toledano-Carrasco 2016 : pl. 22, as Gecarcinus lateralis ). Antero-lateral margins rounded, not delimitated in males; marked by granular margin in females ( Guinot et al. 2025 : figs 9 A , 9 B , 15 A , H. lateralis , H. quadratus , H. nobilii , respectively). Numerous striae along lateral margins of the carapace. Subhepatic striae used as stridulatory pars stridens (see below). Cephalic structures ( Fig. 2F ) Antennules very small, folded obliquely. Antennae very short, completely exposed, visible. Orbits small, with marked outer angle. Eyestalks relatively short, curved ( H. lateralis , see Toledano-Carrasco 2016 : pl. 23, as Gecarcinus lateralis ; Guinot et al. 2025 : fig. 10 B and 10 C , H. lateralis , H. quadtatus , respectively). Proepistome ( Fig. 2F ) Proepistome small, covered by subfrontal plate, thus not visible. Buccal frame, epistome, mxp3 and pterygostome ( Fig. 2F ) Buccal frame short, subcircular to rhomboid, not circumscribed laterally, with its anterior border being the anterior limit of linear anterior margin of epistome. Mxp3 rather small, short, not reaching epistome (except in H. quadratus , see Guinot et al. 2025 : figs 10 C , 14 A ), leaving between them a narrow rhomboid gap, in which mandibles are exposed. Ischium in longitudinal position and merus only slightly obliquely directed, their articulation nearly horizontal. Ischium barely smaller than merus, without longitudinal groove (only a small trace); merus directed slightly obliquely, with anterior margin emarginate but variably,sometimes only slightly, barely concave ( H. quadratus , see Guinot et al. 2025 : figs 10 C , 14 A ) or with distinct notch ( H. lateralis , see Guinot et al. 2025 : figs 10 B , 12 A , B ; H. nobilii , see Guinot et al. 2025 : fig. 15B-D); meri of both sides not joining medially (except in H. quadratus ); palp inserted below merus: its first article fused to merus internal surface and only small portion of last mobile article exposed. Mxp3 exopod completely concealed, as narrow, proportionnally short, conspicuously reduced plate, its apex not reaching ischium-merus articulation; without flagellum ( H. lateralis and H. quadratus , see Tavares 1989 : figs 13g , 14g and 13e, 14e, as G. lateralis , G. quadratus , respectively; Guinot et al. 2025 : fig. 11 B and 11 C , H. lateralis , H. quadratus , respectively). Subhepatic area with many striae, pterygostomial areas glabrous, naked. Chelipeds Male chelipeds massive but not extraordinarily enlarged, very unequal, especially in old males; heterochely and heterodonty usually not or only slightly marked ( Fig. 14A, B ); in rare cases of greatly uneven chelipeds (heterochelic chelae), a more pronounced gap and pronounced heterodonty. No genetic predisposition for right-handedness. Merus smooth ( H. lateralis ) or with only small granules on inner lower margin ( H. quadratus , H. nobilii ); carpus smooth ( H. lateralis , H. quadratus ) or with denticles ( H. nobilii ) on inner upper margin; occlusal margins of fingers with small, spaced teeth on both sides. Sexual dimorphism moderate. Ambulatory legs P 3 moderately spiny.Propodus with unequally developed lateral carinae bearing four rows of weakly developed spines.Dactylus with four rows of small equal spines ( H. lateralis , H. nobilii ) or with six rows of small, unequal spines ( H. quadratus ). Sterno-pleonal cavity and male pleon Sterno-pleonal cavity shallow, short, not close to thoracic sternal suture 2/3, moderately setose; ridge on sternite 4 marked, surrounding telson only when pleon is applied against sternal surface. Male pleon moderately long, with all somites free plus telson; somite 6 with more or less convex lateral margins; pleonal margins only with fringe of setae ( Guinot et al. 2025 : figs 12D and 14 C , H. lateralis , H. quadratus , respectively). Female pleon ( Fig. 9C, D ). See below, Female pleon and pleopods. Thoracic sternum, locking pleonal structures and setal tufts Thoracic sternum wide, narrowing at level of somite 5, thus restricted at level of P 1. Sternite 1 as small triangular tooth, not separated by suture from sternite 2, not recessed; sternite 2 semi-ovate with convex margins; suture 2/3 present, practically straight or barely concave, in open V-shaped ( H. lateralis ); suture 3/4 absent, without lateral trace; sternites 3 + 4 completely fused, with gently concave or nearly straight margins; sutures 4/5 to 7/8 interrupted; sternites 5-7 similarly shaped, sutures well defined; suture 7/8 rather short; sternite 8 not developed medially, totally hidden when pleon is folded; posterior emargination reaching sternite 7 at level of narrow median bridge at level of suture 7/8; another weak median bridge at level of suture 6/7. Deep median line along sternite 7, apparently slightly extending on proximal region of sternite 6 ( Guinot et al. 2025 : figs 12D and 14 C , H. lateralis , H. quadratus , respectively). Locking pleonal structure as prominence rather close to suture 4/5, covered by setae; pleonal sockets not delineated, so pleonal locking non-functional. Patches of more or less dense hydrophilic setae located along first pleonal somites margins of pleon and at its junction with carapace. Male gonopore and penis Male gonopore close to P 5 coxo-sternal condyle, but penis emerging rather far and just below thoracic sternal suture 7/8 ( Guinot et al. 2025 : fig. 13 A , H. lateralis ). G 1 and G 2 ( Fig. 5F ) G 1 short, thick, slightly tapering at extremity, with unequal setae at its tip; apex short; laterally, a very long, narrow, horny, more or less curved tube, not folded and open all along, and exceeding G 1 tip; apex reaching suture 4/6 or exceeding it ( Hartnollius lateralis and H. quadratus , see Tavares 1989 : figs 18e, 19b, as Gecarcinus lateralis ; fig. 19a, as G. quadratus ; H. lateralis , H. quadratus , see Toledano-Carrasco et al. 2021 : fig. 3 A , B , as G. lateralis , G. quadratus , respectively; H. lateralis , see Toledano-Carrasco 2016 : pl. 20, as G. lateralis ; Guinot et al. 2025 : fig. 13 A and 13 C , H. lateralis , H. quadratus , respectively); several horny setae at its base. G 2 very small, without flagellum ( Guinot et al. 2025 : fig. 13 A and 13 C , H. lateralis , H. quadratus , respectively). Vulvae Protruding, oriented nearly horizontally, normally occluded by rigid calcified immobile operculum ( H. lateralis , see Tavares 1989 : fig. 18e, as Gecarcinus lateralis ; Guinot et al. 2025 : figs 13 B and 15 E , H. lateralis , H. nobilii , respectively).

DIAGNOSIS Carapace Carapace broader than long, flat, with hepatic, subhepatic and branchial regions not markedly inflated, widest part of carapace being more or less in line with antero-lateral angles of mesogastric region. Fronto-orbital distance about half of maximum carapace width in adults. Dorsal surface with shallow grooves: cervical groove terminating anteriorly in a pit near orbital angle; median (or urogastric) groove well-defined but shallow; longitudinal mesogastric groove well-defined but shallow, rising towards frontal margin. Numerous striae along lateral margins of the carapace, used as stridulatory pars stridens. Front short, moderately produced and deflexed, with straight lateral margins and upturned lower margin. Mesial lobe of infraorbital margin angular, just joining front edge, completely exposed. Antero-lateral margins rounded, not delimitated in males; marked by granular margin in females. Cephalic structures Antennules very small, folded obliquely. Antennae very short, completely exposed. Orbits typical, outer angle marked. Eyestalks relatively short, curved. Proepistome, epistome and pterygostome Proepistome covered by subfrontal plate, thus not visible. Epistome developed, with one median crest and a lateral crest on each side. Buccal cavity rhomboid. Subhepatic and pterygostomial region glabrous, with many striae. Mxp3 Mxp3 rather small, not reaching epistome (except in H. quadratus n. comb. ), leaving between them a narrow rhomboid gap, in which mandibles are exposed. Ischium in longitudinal position and merus only slightly obliquely directed, their articulation nearly horizontal. Ischium barely smaller than merus, without longitudinal groove (only a small trace); merus directed slightly obliquely, with anterior margin emarginate but variably, sometimes only slightly, barely concave ( H. quadratus n. comb. ) or with distinct notch; meri of both sides not joining medially (except in H. quadratus n. comb. ); palp inserted below merus: its first article fused to merus internal surface and with only small portion of last mobile article exposed. Exopod of mxp3 completely concealed, apex not reaching ischium-merus articulation, as narrow suboval plate; without flagellum. Chelipeds Male chelipeds massive but not extraordinarily enlarged, very unequal, especially in old males; heterochely and heterodonty usually not or only slightly marked; in rare cases of greatly uneven chelipeds (heterochelic chelae), a more pronounced gap and pronounced heterodonty. No genetic predisposition for right-handedness. Merus smooth ( H. lateralis n. comb. ) or with only small granules on inner lower margin ( H. quadratus n. comb. , H. nobilii n. comb. ); carpus smooth ( H. lateralis n. comb. , H. quadratus n. comb. ) or with denticles ( H. nobilii n. comb. ) on inner upper margin; occlusal margins of fingers with small, spaced teeth on both sides. Sexual dimorphism moderate. Ambulatory legs P3 moderately spiny. Propodus with unequally developed lateral carinae bearing four rows of weakly developed spines. Dactylus with four rows of small equal spines ( H. lateralis n. comb. , H. nobilii n. comb. ) or with six rows of small unequal spines ( H. quadratus n. comb. ). Sterno-pleonal cavity and pleon Sterno-pleonal cavity moderately setose, short, not close to thoracic sternal suture 2/3, with marked ridge around telson. Male pleon moderately long, with all somites free plus telson; somite 6 with more or less convex lateral margins. Margins of pleon only with fringe of setae. Thoracic sternum, locking pleonal structures and setal tufts Thoracic sternum wide, narrowing at level of somite 5, thus restricted at level of P1. Sternite 1 as small triangular tooth, not separated by suture from sternite 2, not recessed; sternite 2 semi-ovate with convex margins; suture 2/3 present, practically straight or barely concave, in open V-shaped ( H. lateralis n. comb. ); suture 3/4 absent, without lateral trace; sternites 3 + 4 completely fused, with gently concave or nearly straight margins; sutures 4/5 to 7/8 interrupted; sternites 5-7 similarly shaped, sutures well defined; suture 7/8 rather short; sternite 8 not developed medially, totally hidden when pleon is folded; posterior emargination reaching sternite 7 at level of narrow median bridge at level of suture 7/8; another weak median bridge at level of suture 6/7 ( H. lateralis n. comb. , H. quadratus n. comb. ); deep median line only along sternite 7. Locking pleonal structure as prominence rather close to suture 4/5, covered by setae; pleonal sockets not delineated, so pleonal locking no longer functional. Patches of more or less dense hydrophilic setae located along first pleonal somites margins of pleon and at its junction with carapace. Male gonopore and penis Male gonopore and penis at level of suture 7/8 emerging rather far from P5 coxo-sternal condyle. G1 and G2 G1 slightly tapering at its extremity, with unequal setae at its tip; apex short; laterally, a very long, narrow, horny, more or less curved tube, not folded and open all along, and exceeding G1 tip; several horny setae at its base. G2 very small, without flagellum. Vulvae Protruding, oriented nearly horizontally, normally occluded by rigid calcified immobile operculum.