Macroxenodes jahynyi, Duy-Jacquemin, 2009

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 : 841-842

Macroxenodes jahynyi n. sp.

( Figs 8 ; 9 )

TYPE MATERIAL. — Brazil. Minas Gerais, Uberlândia, Estação Ecologica do Panga, Mata de cerrado, 19°10’59.62”S, 48°24’4.30”W, altitude 830 m, 28.XI.2005, R. Pacheco do Nascimento and B. Jahyny coll., 2 ad. ♀♀ anaesthetized in a nest (cavity in soil near surface) of Thaumatomyrmex mutilatus Mayr, 1887 ( Insecta, Hymenoptera , Formicidae , a specialized predator of Penicillata): ♀ holotype of which the head is mounted on 2 slides, the trunk being in alcohol ( MZUSP); 1 ♀ paratype mounted on 3 slides ( MNHN).

OTHER MATERIAL EXAMINED. — Brazil. Sao Paulo, Rio Claro-UNESP, litter (termite mound), X. 2003, B. Jahyny col., 1 ad. ♀ ( MNHN). — Uberlândia, 1 ♀ from the same nest as holotype and paratype ( MNHN).

Argentina. Diamante, près de l’Institut, 1.XII.1997, N. Fernandez coll., leg. Y. Coineau, 1 ad. ♀ ( MNHN).

ETYMOLOGY. — Th is species is named after one of its collectors, B. Jahyny.

DESCRIPTION

Coloration: brownish, darker on lateral sides of tergites; many trichomes dark brown.

Measurements: body length (without caudal penicillus) 3.90 (holotype) and 4.70 mm (paratype), 4.50 mm in female from Rio Claro, 5 mm in female from Diamante; caudal penicillus length 1.10 mm; head-trichomes length 0.30 mm. Tergites V and VI width 1.40 mm. Tarsus II of 13th leg 224 µm long in paratype, 192 µm in female from Rio Claro, 180 µm in female from Diamante.

Head: eight ocelli on each side. Vertex with one pair of posterior tufts consisting of two rows: anterior sinuous row with 17-22 (left row with 24 in female Rio Claro), posterior row with 6-8 trichomes, the latter in front of internal trichobothrium. Distance between tufts equal to half a rowlength.

Proportions of antennal articles as shown in Figure 9A ; article VI 1.25-1.5 times as long as wide. Antennal article VI with three rows of sensilla (see Fig. 9C ): anterior part of distal row with 2 shorter and thicker basiconica sensilla E, a trifid setiform sensillum s between and below the thick sensilla and one sensillum coelonicum c posterior to E; the other sensilla basiconica generally longer and thinner: 18 on the left antenna ( Fig. 9C ) and 19 on the right antenna in holotype; 19 and 21 in paratype; 15 and 17 in female from Rio Claro; 14 and 15 in female from Diamante. Antennal article VII with two subequal, thick, dorsal sensilla basiconica, one posterior sensillum coeloconicum c and one trifid setiform sensillum s between the two sensilla basiconica ( Fig. 9B ). Three trichobothria of equal size.

Labrum clothed with numerous small cuspidate papillae in addition to three rows of spherical papillae ( Fig. 9D ); 8+8 lamellar teeth on anterior margin. Clypeo-labrum with 14 setae along posterior margin. Lateral expansions of gnathochilarium 4 times as long as the diameter of middle palp, with 27 or 28 sensilla pseudoarticulated at apex (22 and 25 in female from Diamante), middle palpus with 21 sensilla, comprising in holotype 14 long pseudoarticulated sensilla and 7 short sensilla nonarticulated at apex ( Fig. 9E ).

Trunk: observed only in paratype. Except on collum and tergites IX and X, trichomes arranged in two lateral tufts of 20-30 trichomes connected by three trichomic rows: anterior row with 18- 27 trichomes directed towards the head, middle row with 10-14 trichomes and uninterrupted, sinuous, posterior row with 27-39 trichomes directed towards telson; on some tergites, anterior row slightly. Tergites IX and X with only anterior and posterior rows. Anterior row and middle row interrupted in the middle, trichomes of anterior row closer together than those of middle row. Collum with two lateral tufts of 35 trichomes, anterior row of 10 trichomes, middle row of six trichomes, posterior row of 26; lateral protuberance of tergite I with 5 (right) and 7 (left) trichomes in a row.

Legs: in paratype, all articles of the legs bear sensory setae, except first tarsus. Setae on coxa, trochanter and prefemur with an oval base, provided with an acute apical process. Chaetotaxy: coxa I, 1 seta; coxae II to XII, 2 setae (3 setae in four cases); trochanters, 1 seta; prefemora of legs I to XIII, 1 seta and 1-3 (generally 2) small, trifid setae ( Fig. 9H ); almost all femora and tibiae with same small seta as prefemur. Second tarsus with a small seta as shown in Figure 9F .Telotarsus bearing an anterior process with a spinous projection longer than claw, two subequal latero-anterior and posterior spiniform processes; posterior lamellar process thickened and basally pleated ( Fig. 9G ).

Five setae above the anal valve observed in paratype (3 right + 2 left).

Telson: characteristic of the subfamily. Dorsal face of telson with 13 + 13 trichomes a. Trichomes of caudal penicillus with 2 or 3 hooks.

REMARKS

The left antenna of the adult female from Rio Claro is regenerated, with 19 sensilla basiconica and left lateral expansion of gnathochilarium shorter and deformed; right antennal article VI with 17 sensilla on two rows; right lateral expansion of gnathochilarium with 17 sensilla.

AFFINITIES

This species is near to Macroxenodes bartschi (Chamberlin, 1922) , as redescribed by Nguyen Duy-Jacquemin & Condé (1984). The antennal sensilla of article VI are more numerous in the new species, always including two shorter and thicker sensilla basiconica on anterior part of the distal row; these two sensilla are not always present in M. bartschi , sometimes there is only one shorter ( Fig. 9I ). The lateral palp expansion of the gnathochilarium is longer in M. jahynyi n. sp., with a maximum 28 sensilla, as opposed to 13 in bartschi . There are only 3 anterior rows of spherical papillae on the labrum, whereas M. bartschi has 4 or 5 rows.

The two new species M. navassaensis n. sp. and M. jahynyi n. sp. are the fifth and sixth species included in genus Macroxenodes . The others are meinerti , the type species, from Venezuela (Caracas); M. bartschi from the Florida Keys; M. poecilus (Chamberlin, 1923) , redescribed by Condé & Nguyen Duy-Jacquemin (1987), from Santa Inez Island, Gulf of California; and M. amazonicus ( Ishii et al. 1999) from Brazil, Amazonas, Ilha de Marchantaria and environs of Manaus.

Figures

FIG. 8.— Macroxenodes jahynyi n. sp.,adult female,habitus,dorsal view, 5 mm in length. Photograph by B. Jahyny.

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.