Phryssonotus brevicapensis Nguyen Duy-Jacquemin , Uys & Geoffroy

Duy-Jacquemin, Monique Nguyen, Uys, Charmaine & Geoffroy, Jean-Jacques, 2011, Two remarkable new species of Penicillata (Diplopoda, Polyxenida) from Table Mountain National Park (Cape Town, South Africa), ZooKeys 156, pp. 85-103 : 90-94

Phryssonotus brevicapensis Nguyen Duy-Jacquemin, Uys & Geoffroy sp. n. Figs 6-9

Type material.

South Africa, Cape Town,Table Mountain National Park. Tokai S, site 30, Fynbos, altitude 310 m, 34°04'01S, 18°24'03E, leaf litter, 24/XI/2008, holotype adult male (no. 16a) and 1 paratype adult male (no. 16b) (MNHN). Other paratypes: adult male (no. 1) (MNHN), Newlands, site 4, pine plantation, altitude 260 m, 33°58'24S, 18°26'27E, sugar–baited ant trap, 15/I/2009; adult female (no. 20) (MNHN), Tokai S, site 31, pine plantation, altitude 300 m, 34°03'54S, 18°24'10E, decaying log, 19/I/2009; adult female (no. 11) (MNHN), Constantia Nek, site 19, felled pine, altitude 330 m, 34°00'20S, 18°24'45E, pitfall trap, 02/II/2009; male with 14 pl (subadult) (no. 8) (MNHN), Cecilia, Spilhaus, site 16, felled pine, altitude 470 m, 34°00'04S, 18°24'46E, pitfall trap, 23/0I/2009; female with 14 pl (subadult) (no. 13) (MNHN) and female with 12 pl (no. 15) (MNHN), Tokai N, site 27, pine plantation, altitude 330 m, 34°02'23S, 18°23'53E, leaf litter, 21/XI/2008; 2 larvae with 10 pl and 8 pl (no. 12) (MNHN), Orange Kloof, site 22, pine plantation, altitude 240 m, 34°00'23S, 18°24'02E, leaf litter, 18/XI/2008. All specimens collected by Charmaine Uys.

1 male with 14 pl (no. 6b) was collected at the same site as a male with 12 pl of Propolyxenus squamatus sp. n. (no. 6, used for SEM).

Etymology.

Refers to the shorter body length and development compared to the most closely related species, Phryssonotus capensis .

Diagnosis.

10 ocelli; 5 trichomes B close to the smallest trichobothrium (tc) as in Phryssonotus capensis . Differing from Phryssonotus capensis with 10 rings in adults instead of 11 (without telson), 15 leg pairs instead of 17, and the attendant shorter post–embryonic development. Males with 3 pairs of coxal glands on legs 7-9.

Description of adults, males and females.

Measurements. Body length (without caudal penicil): 4.00-4.50 mm; caudal penicil length: 0.90-1.00 mm (Figs 6, 7A).

Head with 10 ocelli on each side (Fig. 8A); 3 trichobothria with the anterior 1 (tc) possessing a much shorter sensory hair than the other 2 (ta and tb). 5 short frontal trichomes B1-B5 and 1 long, curving trichome A (Fig. 8B).

Proportions of antennal articles as in Fig. 8C. Antennal article VI with 3 basiconic sensilla (Fig. 8C, E): 2 anterior (a), which are shorter and slightly thinner than the posterior one (p); 1 anterior setiform sensillum (s) and 1 posterior coeloconic sensillum (c); antennal article VII (Fig. 8D) with 2 basiconic sensilla, the anterior (a) slightly shorter than the posterior one (p), 1 setifom sensillum (s) between the 2 basiconic sensilla and 1 posterior coeloconic sensillum (c).

Surface of labrum with numerous, small, short cuspidate papillae; papillae of anterior 3 or 4 rows larger, the size of the following papillae decreasing progressively, the smaller ones in the posterior third; about 30 lamellate teeth at anterior margin. Clypeo–labrum with ca. 10 setae, about 3/4 maximum width of labrum. Lateral expan sions of gnathochilarium about twice as long as diameter of middle palp, with 21-25 sensilla, middle palp with 26-29 sensilla, of which antero–medial sensilla shorter than the others (Fig. 8F).

Trunk of adults with 11 tergites (including collum and telson) and 15 pairs of legs (Fig. 7A). Collum with 2 medial, separate oval clusters comprising 80-90 barbate trichomes and a lateral group of 8-14 barbate trichomes. Tergites II–X with submedial and posterior rows of scale–shaped trichomes directed caudally (Fig. 7D), the posterior row arranged along the posterior margin of the tergite; 1 area of aligned barbate trichomes at end of each row, except on tergite II where are 35-40 barbate trichomes arranged, on each side, in 2 diagonal lines above the first scale–row; 2 short rows of barbate trichomes at end of submedial scale–row and 4 (sometimes 5 on tergite II and X) short rows of barbate trichomes at end of posterior scale–row. The number of scales by row ranges from 29-62 on tergites II–X.

Legs short (Fig. 9A), with 8 articles except on legs 1, 14 and 15; last 2 pairs (14-15) without telotarsus, tarsus II terminated in palettes (Figs 7B, C; 9E, F); palettes covered by numerous cuticular setae of different types (Figs 7B; 9F); apodeme of palettes (pa) and claws (ca) extending into distal part of trochanter and linked to the flexor unguiculi muscle, which allows a great flexibility of the palette of the leg pairs 14 and 15, as well as to the claws of legs 1-13, in accordance with the description given by Manton (1956) for Polyxenus lagurus . Legs 1-13 with each trochanter, prefemur (Fig. 9B), femur, tibia and tarsus I bearing a single long and very fine seta; seta of second tarsus longer than claw (Fig. 9C). Legs 14 and 15 with only 2 setae on prefemur (Fig. 9E). Telotarsus bearing an anterior process (ap) with spinous projection longer than claw; lamellate process (plp) thickened and basally pleated; claw with 2 subequal, strongly pointed latero–anterior and posterior teeth (Fig. 9C, D).

Female: large vulval sacs elongated, reaching as far as fourth pair of legs and bearing numerous small setae inserted in parallel circles and sparse longer setae.

Male: all areas of penis with usual thin cuticular setae and about 15 longer setae (holotype). Coxal glands on legs 7-9.

Conical telson with a transverse row of 15 (male no. 1), 10 (male no. 16b) or 14 (female no. 20) scale–shaped trichomes with each lateral end prolonged by barbate trichomes; long barbate trichomes on distal part.

Subadults.

1 male, 1 female: Measurements: Body length (without caudal penicil): 3.20 mm (male no. 8) and 3.90 mm (female no. 13); caudal penicil length: 0.90 mm. 14 pairs of legs, the 14th terminating in a palette; 1 pair of appendage–buds on lateral side of anal valves, from which 15th pair of legs will develop, the future adult stadia having the leg pair 15 terminating in palettes. Other characters as in adults, except no scale–row on telson.

Male: Coxal glands on legs 7-9.

Female: large vulval sacs elongated, reaching as far as fourth pair of legs.

Stadium VII.

1 female (no. 15) with 12 pl; body length (without caudal penicil): 3.80 mm; caudal penicil length: 0.80 mm; 10 ocelli, vulval sacs elongated, reaching as far as third pair of legs. 2 pairs of external buds.

Stadium VI.

1 juvenile male with 10 pl; body length (without caudal penicil): 3.30 mm; 10 ocelli; rudimentary coxal glands on legs 7 and 8. 2 pairs of external buds.

Stadium V.

1 larva with 8 pl; body length (without caudal penicil): 2.70 mm; 9 ocelli. 2 pairs of external buds.

Discussion.

Phryssonotus brevicapensis sp. n. exhibits all the general characters usually present in the family Synxenidae : long and thin dark barbate trichomes all along the body, tergites covered by tergal scale–shaped trichomes that are striated and arranged in 2 transverse rows along all the tergites except the collum; telson subconical; elongated vulvae; and last 2 leg pairs terminating in palettes instead of claws. It also shows the typical structure of the scale–shaped trichomes found in the genus Phryssonotus . Phryssonotus brevicapensis sp. n. differs from other members of the genus in having 11 tergites and 15 pl; the last 2 pairs (14th and 15th) terminating in palettes; and males with 3 pairs of coxal glands on legs 7-9. These differences are strongly related to biology and development, and justify the creation of a new species. All other species of Phryssonotus have 12 tergites and 17 pairs of legs with the last 2 pairs (16th and 17th) terminating in palettes, and males with 3 pairs of coxal glands on legs 9-11. Due to its shorter length and the position of the coxal glands on legs 7-9, it is similar to Condexenus biramipalpus . The elongated vulvae (ovipositors) of the females also resemble thos e of Condexenus species in reaching as far as the fourth pair of legs, as opposed to sixth at most in other Phryssonotus species.

Phryssonotus brevicapensis sp. n. is most closely related to Phryssonotus capensis , in having 10 ocelli and 5 short frontal trichomes B1 to B5, Phryssonotus capensis has 5-6 trichomes B ( Silvestri 1923).

Following the discovery of Condexenus biramipalpus from Namibia, it is of great interest to add Phryssonotus brevicapensis sp. n. as the second example of reduction of ring and leg number in the family Synxenidae , whose representatives bear the largest number of segments among the Penicillata. This supports the hypothesis of a trend towards a shortened postembryonic development during the course of evolution of Polyxenida ( Condé 1969 and Nguyen Duy–Jacquemin 2006). The comparison of the pattern of development is emphasised in the improved scheme (Fig. 10), in which the shortest development pattern is seen in Lophoturus madecassus (Marquet et Condé, 1950). The two new species described in the present work strongly support this evolutionary trend among penicillate families.