Sphaeroniscus frontalis, RICHARDSON, 1914

Schmidt, Christian, 2007, Revision of the Neotropical Scleropactidae (Crustacea: Oniscidea), Zoological Journal of the Linnean Society 151, pp. 1-339 : 59-60

SPHAERONISCUS FRONTALIS RICHARDSON, 1914

Sphaeroniscus frontalis Richardson, 1914 – Van Name (1936).

Sphaeroniscus frontalis Richardson, 1912 (*) – Leistikow & Wägele (1999); Schmalfuss (2003).

Sphaeroniscus flavomaculatus – Vandel (1968) (misidentification).

Material examined

Types: Two ♂ (lectotype ♂ 5.0 mm wide described here, others become paralectotypes) , two ♀ ( Colombia, Argelia, 4°22′ N, 74°45′ W, near Viota) , one ♂ (‘ Colombia, Buenavista , nr. Viota’, all specimens collected by O. Fuhrmann, BMNH 1928.5.1.84- 87 syntypes) .

Other samples: One ♀ m (5.1 mm wide) ( Colombia, ‘Capote, locality in the Magdalena valley ca. 250 km N. of Bogotá, approx. 40 km E of Barrancabermeja between the tributaries Carare and Opon, moist tropical rainforest, leaf litter, humus, leg. H. Sturm, 29 July to 4 August 1968, CV, identified as Sphaeroniscus flavomaculatus by Vandel) .

Description ( Figs 173–175 )

Males 5.0– 5.2 mm wide, female maximum 6.3 mm wide. Tergites brown with pale muscle insertion spots. Cephalothorax, coxal plates, pleon-epimera and uropods pale. Second antenna fifth article with little pigment, flagellum pale. Pereiopods and pleopods not pigmented. After Richardson (1914), six specimens from Argelia had a ‘uniform orange brown color, with light wavy lines of yellow on either side of the median line’, whereas one specimen from Buenavista was ‘dark grey, with wavy lines of yellow on either side of the median line’. Endoantennal conglobation. Dorsal surface smooth and shiny, with only very small tricorn setae. Noduli laterales could not be seen without dissection. Cephalothorax with frontal shield only slightly exceeding vertex. Behind frontal shield a transverse furrow, bent backwards at both ends and then becomes obsolete. First coxal plate with schisma, inner lobe distinctly shorter but laterally more protruding. Anterior corner of first coxal plate delimited by a weak ridge, with striation. Second coxal plate with anterior thickened sulcus. All margins of tergites, pleon-epimera and uropod sympodites fringed with minute, hyalinous hairs or scales. Vandel’s female specimen has agglutinated secret drops regularly at the ventral anterior corners of the coxal plates. This may indicate the presence of gland pores or gland pore fields.

Eyes composed of c. 15–20 ommatidia; because of the shallow lenses and the degradation of the pigment (due to preservation), the exact number could not be counted.

First antenna three-jointed. Second antenna with three-jointed flagellum, apical cone longer than the distal article. Mandibles with four-cusped pars incisiva, lacinia mobilis on left mandible with three cusps, on the right with two cusps, hairy lobe with one hairy seta on right and two on left mandible, pars molaris represented by a tuft of numerous hairy setae, and one hairy seta each between hairy lobe and pars molaris. External face of mandible with some small scale setae. First maxilla lateral endite with lateral group of four stout teeth and mesal group of six more slender teeth, five of them with cleft tips. A triangular lobe and a slender seta, which bears some subapical setules, on the caudal face beside lateral group. Beside mesal group a subapical, extremely small seta on the caudal face. Lateral margin of lateral endite distally fringed with hairs (pectinate scales). Mesal endite of first maxilla distally rounded, with two subapical penicils (one of which is strongly bent in the examined specimen which seems to be an artefact) of unequal size. Second maxilla apically bilobate, mesal lobe with a distal field of presumed sensilla on the frontal face, and a slightly broader lateral lobe covered with pectinate scales. Maxilliped basis roughly rectangular, with small scale setae and scales; near the insertion of palp on caudal face some longer scales resemble the scales of water-conducting structures. Epipodite slightly hairy at its tip. Endite elongate rectangular, covered with pectinate scales and bearing a small seta on the caudal face and a penicil on frontal face, near inner corner. Maxilliped palp proximal article with only one large seta near mesal margin, second article on mesal margin with two tufts of several equal setae, distal tuft on a long socket and with two single setae beside it; lateral margin with one slender and one broad seta. Distal article with apical tuft of numerous small setae, and three single setae on the lateral margin. Some pectinate scales are also found in the medioproximal region of the second article.

Pereiopod 1 with antennal brush composed of rather long scales on merus. Male pereiopod 7 carpus with dorsofrontal tooth-like process near the distal margin. Water-conducting scales could be seen only on the base and near the articulation with the ischium (the other scales may be absent or only be rubbed off after the death of the specimen). Dactylus with inner claw much shorter than outer claw, ungual seta and distally setulate dactylar seta.

Pleopod 1 exopodite with respiratory field, the following without conspicuous structures. Lateral margin with numerous (17) small marginal setae. Male pleopod 1 endopodite with a row of 34 small, spineshaped setae along the dorsal spermatic furrow and a slight subapical swelling on the mesal margin, bearing the distalmost three of these setae. Pleotelson with rounded triangular tip and concave sides. Uropod sympodite approximately as long as broad, with angular outer corner, exopodite projecting beyond endopodite and sympodite, slightly shorter than the visible portion of the sympodite. Dorsal face of uropod sympodite with a group of gland pores.

Apomorphies

1. uropod sympodites on the dorsal face with a group of gland pores

2. slight subdistal swelling of male pleopod 1 endopodite

Geographical distribution (Map Fig. 172 )

Colombia.

Remark

Sphaeroniscus frontalis is distinguished from S. flavomaculatus by the non-protruding frontal shield and the characters indicated in the key. Otherwise, it is very close to S. flavomaculatus , as Richardson (1914) stated.

Figures

Figure 172. Geographical distribution of Sphaeroniscus flavomaculatus (1), S. frontalis (2), S. gerstaeckeri (3), S. pilosus (4), and S. quintus (5).

Figure 173. Sphaeroniscus frontalis Richardson, 1914: ♀m, c. 11 × 5.1 mm (Colombia, Capote, 250 km north of Bogota, 40 km south-east of Barrancabermeja, leg. H. Sturm, 29 July to 4 August 1968, MNHN).

Figure 174. Sphaeroniscus frontalis Richardson, 1914: ♀m, c. 11 × 5.1 mm, mouthparts (Colombia, Capote, 250 km north of Bogota, 40 km south-east of Barrancabermeja, leg. H. Sturm, 29 July to 4 August 1968, MNHN).

Figure 175. Sphaeroniscus frontalis Richardson, 1914: lectotype ♂, 5 mm wide, pereiopod 7 frontal, pleopod 1 + genital papilla frontal, cephalothorax frontal, coxal plates 1 and 2 ventral (Colombia, ‘Buenavista near Viota’, leg. O. Fuhrmann, BMNH 1928.5.1.84-87).