Trichorhina silvestrii Arcangeli, 1936

Cifuentes, Julio, Bernabé, Iván Escarabajal- & Da Silva, Luís P., 2025, The genus Trichorhina Budde-Lund, 1908 (Crustacea, Isopoda, Platyarthridae) in the Ibero-Balearic region, with descriptions of three new species, Zootaxa 5725 (3), pp. 341-370 : 347

Trichorhina silvestrii Arcangeli, 1936

Figs 5–9

Material examined. Portugal: 2 males ( LPS737 a), Bragança, Frechas , 41°24’21” N, 7°09’22” W, 5/I/2023, leg. L.P. Da Silva ; 6 females ( LPS737 b), male ( LPS738 ), same data as preceding ; female ( LPS127 ), Coimbra, Praia do Cabedelinho , 40°08’29” N, 8°51’60” W, 6/III/2022, leg. L.P. Da Silva ; male ( JC607 [ex. LPS129a]), Coimbra, Praia do Cabedelinho , 40°08’27” N, 8°51’55” W, 06/III/2022, leg. L.P. Da Silva ; 4 females ( LPS129 b), same data as preceding ; female ( LPS130 ), Coimbra, Praia do Cabedelinho , 40°08’28” N, 8°51’54”, 06/III/2022, leg. L.P. Da Silva.

Description. Some specimens with faint network of very light violet chromatophores on posterior edge of cephalon and tergites, others depigmented. Ocular apparatus with four black ommatidia ( Fig. 7C ).

Integumentary characters ( Figs 6 , 7A–C , 8A–C ): Dorsal integument lacks granulations, with triangular scales, large fan-shaped scale-setae, along with smaller ones. Noduli laterales very close to posterior edge on all tergites but away from lateral edge.

Somatic characters ( Figs 7A–C , 8C ): Cephalon slightly inserted into anterior concavity of pereonite I, following pereon. Small triangular median lobe with rounded apex; very small rectangular lateral lobes. Pereonites I and II posterior corners convex, straight in pereonite III, and small angular projection in pereonites IV to VII. Pleon slightly retracted in relation to pereon; small neopleura and posterior corner of pleonite V shorter than posterior edge of uropod protopods. Triangular telson, much shorter than wide, slightly curved sides and acute tip.

Appendages ( Figs 9A–E , 10A–C ): Mandibles with molar penicil dichotomised into three branches; left mandible with 1+1 free penicils, right with one. Maxillula inner endite with two penicils, outer endite with seven teeth, two bifurcated. Maxilla and maxilliped as in Fig. 9D, E . Antennula with three segments, second barely noticeable, almost embedded in first; third with 9 short aesthetascs and lateral triangular spine. Antennae barely surpassing posterior edge of pereonite I; flagellum with two segments, first almost one-third length of second. Uropod protopods much shorter than telson tip; endopods slightly shorter than exopods, both conical and small.

Sexual characters: Pereopods without sexual differentiation ( Fig. 10D ). Male pleopod I ( Figs 7D , 11A–B ) with long and straight endopod and some spines at tip; sub-quadrangular exopod with few small teeth on posterior edge. Male pleopod II ( Figs 7E , 11C–D ) with long endopod acutely tapering; triangular exopod with long distal part, bearing teeth and setae on external edge. Male pleopod exopods III to V as in Fig. 11E–G , female exopods as in Fig. 11H–L .

Figures

FIGURE 5. Trichorhina anophthalma Arcangeli, 1935, A–G, male specimen (JC687); H–L, female specimen (LPS567): A, endopod I; B, exopod I; C, endopod II; D, exopod II; E, exopod III; F, exopod IV; G, exopod V; H, exopod I; I, exopod II; J, exopod III; K, exopod IV; L, exopod V. Scale bars: A–L = 0.1 mm.

FIGURE 6. Relation between Noduli laterales coordinates d/c (y-axis) and b/c (x-axis) multiplied by 100 for all studied species. A, Trichorhina anophthalma Arcangeli, 1935, JC687; B, Trichorhina cascaisensis sp. nov., LPS917b; C, Trichorhina ornata sp. nov., LPS850; D, Trichorhina silvestrii Arcangeli, 1936, LPS129b; E, Trichorhina solorzanoi sp. nov., MNCN 20.04/21002-5.

FIGURE 7. Trichorhina silvestriiArcangeli, 1936,A–C, female specimen (LPS129b); D–E, male specimen (JC607):A, habitus; B, pleon, telson and uropods; C, cephalon, lateral view; D, exopod I; E, exopod II. Scale bars: A = 0.5 mm; B–E = 0.1 mm.

FIGURE 8. Trichorhina silvestrii Arcangeli, 1936, A–C, female specimen (LPS129b): A, scale-setae; B, noduli laterales b/c and d/c ratios (y axis) and tergite number (x axis); C, pleon, telson and uropods. Scale bars: A = 0.01 mm; C = 0.1 mm.

FIGURE 9. Trichorhina silvestrii Arcangeli, 1936, A–E, male specimen (JC607): A, left mandible; B, right mandible; C, maxillula; D, maxilla; E, maxilliped. Scale bars: A–E = 0.1 mm.

FIGURE 10. Trichorhina silvestrii Arcangeli, 1936, male specimen (JC607):A, antennula; B, antenna; C, uropod; D, pereopod VII. Scale bars: A–D = 0.1 mm.

FIGURE 11. Trichorhina silvestrii Arcangeli, 1936, A–G, male specimen (JC607); H–L, female specimen (LPS127): A, endopod I; B, exopod; C, endopod II; D, exopod II; E, exopod III; F, exopod IV; G, exopod V; H, exopod I; I, exopod II; J, exopod III; K, exopod IV female; L, exopod V. Scale bars: A–L = 0.1 mm.