Phryssonotus, Scudder, 1885

Duy-Jacquemin, Monique Nguyen & Azar, Dany, 2004, The oldest records of Polyxenida (Myriapoda, Diplopoda): new discoveries from the Cretaceous ambers of Lebanon and France, Geodiversitas 26 (4), pp. 631-641 : 636-638

Phryssonotus sp. ( Figs 5 ; 6 )

MATERIAL EXAMINED. — Immature female, specimen number SA 5.1, deposited in the MNHN.

Locality and horizon: from the amber of Salignac (Haute-Provence, France). Albo-Cenomanian period (100-95 million years). The amber piece is mounted between coverslips in Canada balsam medium.

DESCRIPTION

Immature female ( Figs 5 ; 6 )

The posterior part of body is lacking; only the head, seven tergites and 10 pairs of legs are present; only the tarsus II and telotarsus of the eleventh pair remain ( Fig. 6A ) because the posterior part of the body is broken. The slightly elongated vulval sacs demonstrates that the specimen is not an adult; it is probably an immature female with 12 or 14 pairs of legs (adults have 17 pairs of legs), the stage with 11 pairs of legs does not exist in Synxenidae .

Measurements. Body length up to eleventh pair of legs = 2.40 mm.

Head. Only four right ocelli are visible, the remaining ocelli cannot be observed; left antenna with eight articles; only some setiform sensilla are visible on the articles. Right antenna with only three basal articles. Labrum not visible. Lateral expansion of gnathochilarial palp very long (200 µm), with 16 visible sensilla on right palp and 18 on left palp ( Fig. 6B ).

Trunk. The scale-shaped trichomes of the tergites are often lacking or detached from their insertion ( Fig. 6C ). One easily visible seta on tarsus II longer than telotarsus and one seta on the posterior edge of each article ( Fig. 6D ). The caudal penicil is unknown because the posterior part of the body is missing.

Figures

FIG. 5. — Phryssonotus sp., immature female without posterior part of body, length: 2.40 mm (SA 5.1), ventral view.

FIG. 6. — Phryssonotus sp., immature female (SA 5.1); A, habitus, dorsal face, ventral legs and vulval sacs shown with dotted lines; B, palpi of gnathochilarium; C, scale-shaped trichomes of tergites, detached from their insertions; D, right leg V. Abbreviations: V, vulval sac; II-VII, tergite II to VII. Scale bars: A, 0.1 mm; B-D, 50 µm.