Macroxenodes Silvestri, 1948

Duy-Jacquemin, Monique Nguyen, 2009, Revision of the genera of Polyxenidae bearing pseudoarticulated gnathochilarial sensilla (Diplopoda, Polyxenida, Polyxenidae), with the description of two new species, Zoosystema 31 (4), pp. 829-848 : 834

Genus Macroxenodes Silvestri, 1948

TYPE SPECIES. — Polyxenus meinerti Silvestri, 1898 .

REDEFINITION OF THE GENUS

Trichomes short and thick.

Setiform sensilla with three spines on antennal articles, with three or four spines on prefemora, femora and tibiae.

Head: eight ocelli on each side. Vertex with one pair of posterior tufts not separated from the anterior tufts and consisting of two rows (anterior and posterior).

Antennal article VI with five or more sensilla basiconica, one setiform sensillum between the two anterior sensilla basiconica and one sensillum coeloconicum on the distal row of sensilla basiconica ( Figs 4E, D ; 7C, D ; 9C, E ). Antennal article VII with two short, thick sensilla basiconica, one setiform sensillum between them and one sensillum coeloconicum posterior ( Figs 4C ; 7B ; 9B ). Three trichobothria of equal size with cylindrical funiculi ( Figs 4A ; 7E ).

Whole area of labrum clothed with numerous small and varied cuspidate papillae (also called cuticular setae), in addition to two to six rows of larger spherical papillae ( Figs 5A ; 7F ; 9D ) and armed with lamellar teeth on anterior margin. Outer palpus of gnathochilarium with sensilla pseudoarticulated at apex and middle palpus with pseudoarticulated sensilla except for 7-9 short antero-median sensilla.

Trunk: two lateral tufts of trichomes on each tergite connected by trichomic rows. Tergites II to VIII or IX with three trichomic rows: an anterior row with trichomes directed anteriorly towards the head, a median and a posterior row directed towards the telson. The posterior row is sinuous and uninterrupted; trichomes of middle row more spaced than in the anterior and posterior rows ( Fig. 11C ).

Legs: setae on coxae, trochanters and prefemora with subcylindrical, elongated, naked funiculi ( Figs 5F, G ; 7J ). Other small, oval setae (= setiform sensilla) on prefemora, femora and tibiae ( Figs 5D, E ; 7H, I ). Tarsi II with one seta ending in a point ( Figs 5H ; 7K ; 9F ). Pretarsus bearing an anterior process with a spinous projection slightly longer than the claw and posterior lamellar process longer than the claw, with thickened and pleated basal part.Claw with two strongly pointed and subequal anterolateral and posterolateral teeth ( Figs 5I ; 7L ; 9G ).

Telson: two latero-dorsal penicilli of hooked trichomes joined side by side. Dorsal face of telson with a few barbate trichomes a, one oval-shaped group composed of barbate trichomes c and one barbate antero-internal trichome b ( Fig.6D ).Ventral face with a subrectilinear row of barbate trichomes (v: Fig. 6C, E ) located on edge of penicillus of hooked trichomes, usually with two to three hooks ( Fig. 6B ).

Figures

FIG. 4. — Macroxenodes meinerti (Silvestri, 1898): A, vertex, collum and left part of tergite II of female no. 3; B, left antenna of female no. 1; C, D, sensilla on left antennal articles VII and VI of the male; E, sensilla on right antennal article VI of the female no. 1. Abbreviations: c, sensillum coeloconicum; E, short and thick sensilla basiconica; l.p, lateral protuberance on collum; s, setiform sensillum. Scale bars: A, B, 50 μm; C-E, 25 μm.

FIG. 7. — Macroxenodes navassaensis n. sp.: A, right antenna of paratype; B, C, sensilla on right antennal articles VII and VI of holotype; D, sensilla on left antennal article VI of paratype, the new sensilla shown with dotted lines will appear after exuviation; E, left part of head of holotype with insertions of dorsal trichomes; F, labrum of paratype, only part of cuticular setae shown; G, right palpus of gnathochilarium of holotype; H-L, holotype; H, I, small setae of prefemora of right legs III and VII; J, coxal seta of right leg I; K, seta of tarsus II of right leg VI; L, telotarsus of right leg III. Abbreviations: a, anterior sensillum basiconicum; c, sensillum coeloconicum; i, intermediate sensillum basiconicum; p, posterior sensillum basiconicum; s, setiform sensillum. Scale bars: A, E, 50 μm; B-D, F-L, 25 μm.

FIG. 9. — Macroxenodes jahynyi n. sp.: A-E, female holotype; A, left antenna; B, C, detail of sensilla on articles VII and VI of same antenna; D, labrum, only part of cuticular setae shown; E, left palpus of gnathochilarium; F-H, female paratype; F, seta of tarsus II telotarsus of left leg XI; G, telotarsus of same leg;H, seta of prefemur of left leg VI;I, right antennal article VI of male no. 2 of M. bartschi (Chamberlin,1923) (after Nguyen Duy-Jacquemin & Condé 1984).Abbreviations:c, sensillum coeloconicum;E, short and thick sensilla basiconica; s, setiform sensillum. Scale bars: A, E, 50 μm; B-D, F-I, 25 μm.

FIG. 5.— Macroxenodes meinerti (Silvestri,1898):A, labrum of male,only part of cuticular and posterior setae shown;B, right palp of male; C, left leg V of female no. 3; D, three small prefemoral setae of the same leg; E, tibial seta of the same leg; F, G, large setae of prefemur and trochanter of the same leg; H, I, seta of tarsus II and telotarsus of left leg V of male. Scale bars: A, B, D-I, 25 μm; C, 50 μm.

FIG. 11. — Insertions of trichomes on tergite VIII in adult females: A, Chilexenus rosendinus (Silvestri,1903),lectotype; B, Macroxenus rubromarginatus (Lucas, 1846), from Ifrane; C, Macroxenodes meinerti (Silvestri, 1898), cotype; D, Afraustraloxenodes namibiensis Nguyen Duy-Jacquemin, 2003, paratype. Scale bars: 50 μm.

FIG. 6. — A-D, Macroxenodes meinerti (Silvestri, 1898); A, B, distal parts of barbate and hooked trichomes of caudal penicillus of male; C, ventral face of telson of male, dorsal trichomes shown with dotted lines; D, dorsal face of telson of male; E, M. navassaensis n. sp., caudal view of female paratype. All the biggest insertions belonging to barbate trichomes are shown; only part of insertions of hooked trichomes shown; dorsal trichomes a with dotted lines. Abbreviations: a1-a10, insertions of barbate trichomes a; b, insertion of trichome b; c, group of trichomes c; v1-vX, insertions of ventral barbate trichomes on edge of penicillus. Scale bars: A, B, D, 25μm; C, E, 50 μm.