Sundageophilus bidentatus, Bonato, Lucio, Klarner, Bernhard, Widyastuti, Rahayu & Scheu, Stefan, 2016

Bonato, Lucio, Klarner, Bernhard, Widyastuti, Rahayu & Scheu, Stefan, 2016, The first geophilid centipedes from Malesia: a new genus with two new species from Sumatra (Chilopoda, Geophilidae), ZooKeys 605, pp. 53-71 : 55-61

Taxon classification Animalia Geophilomorpha Geophilidae

Sundageophilus bidentatus sp. n.

Diagnosis.

A Sundageophilus species with cephalic plate ca. 1.4-1.5 times as long as wide; first maxillary telopodite apparently composed of a single article; a distinct denticle on the distal part of the trochanteroprefemur; tarsungulum with two basal denticles, one dorsal to the other; 33 or 35 pairs of legs; no ventral pore-fields along the trunk; ultimate metasternite 1.7-1.8 times as wide as long, anteriorly ca. 2.0 times as wide as posteriorly, lateral margins slightly convex; two coxal pores on each coxopleuron, along the lateral margin of the metasternite; telopodites of the ultimate pair conspicuously swollen in the female, unknown in the male, apparently composed of only five articles because of the indistinct articulation between trochanter and prefemur; some articles of the ultimate leg pair with disto-ventral bulges covered with denser, longer setae, and a tuft of tiny spines replacing the pretarsus.

Material examined.

Holotype. ♀ with gonopods partially developed, body length 6.9 mm, head width 220 µm; some legs broken and missing, including one of the ultimate pair; originally entire, subsequently divided in three pieces, (i) head, (ii) forcipular segment and leg-bearing segments 1-16, (iii) leg-bearing segments 17-33 and postpedal segments; collected Nov. 2013, by B. Klarner; in ethanol, LIPI macrosoilBO4a13_chilo144.

Type locality. Indonesia, Sumatra, Bukit Duabelas, oil palm plantation, research site BO4, 02°03'02"S, 102°45'12"E, ca. 30 m a.s.l., from upper soil layer (0-5 cm).

Other specimens examined. 1 ♀, from Bukit Duabelas, secondary rainforest, research site BF2, 01°58'55"S, 102°45'03"E, ca. 80 m a.s.l., from upper soil layer (0-5 cm), same date and collector as holotype, PD5768; 6 ♀♀, from Bukit Duabelas, secondary rainforest, research site BF3, 01°56'34"S, 102°34'53"E, ca. 90 m a.s.l., from upper soil layer (0-5 cm), same date and collector as holotype, LIPI macrosoilBF3a13_chilo178-183; 1 ♀, from Harapan, secondary rainforest, research site HF3, 02°10'30"S, 103°19'58"E, ca. 60 m a.s.l., from upper soil layer (0-5 cm), same date and collector as holotype, LIPI macrosoilHF3c13_chilo17; 1 specimen, sex unknown because body posterior part missing, from Harapan, jungle rubber agroforest, research site HJ2, 01°49'32"S, 103°17'39"E, ca. 80 m a.s.l., from upper soil layer (0-5 cm), same date and collector as holotype, PD5767.

Etymology.

" bidentatus " means "with two teeth" and refers to the presence of two distinct basal denticles on each forcipular tarsungulum.

Description.

Description of holotype (♀, LIPI macrosoilBO4a13_chilo144). See also Figs 1A, 1C, 2, 3.

General features. Body remarkably narrow, almost uniformly wide for most part of the trunk, only slightly narrowing posteriorly. Legs relatively short, most of them ca. 0.2 mm long. Colour (in ethanol) almost uniformly pale yellow, but cephalic plate, forcipular condyles, tarsungula, and leg pretarsi darker.

Cephalic capsule. Cephalic plate subrectangular, ca. 1.4-1.5 times as long as wide, ca. 1.1 times as wide as the forcipular tergite, the lateral margins slightly convex; scutes approximately isometric and up to 10 µm in the anterior half of the cephalic plate, distinctly elongate longitudinally and up to 18 µm long in the posterior half; frontal line absent; setae up to ca. 30 µm long. Clypeus ca. 1.5-1.6 times as wide as long, with lateral margins complete; uniformly areolate, the scutes being up to 10 µm wide, without a distinct clypeal area; a total of 4 setae arranged in two pairs, one anterior to the other. Pleurites uniformly areolate, without setae. Both the intermediate and the lateral parts of the labrum separated from the clypeus by complete sulci; the intermediate part ca. 2.5 times as wide as long, the lateral parts far apart from each other.

Antennae. Slender, ca. 3.6 times as long as the head width. Intermediate articles up to ca. 1.2 times as long as wide. Article XIV ca. 2.2 times as long as wide, ca. 1.9-2.0 times as long as article XIII and slightly narrower than the latter. Setae gradually denser and shorter from the basal articles to the distal ones, both ventrally and dorsally, in particular up to 40 µm long on article I but less than 20 µm long on article XIV. Apical sensilla ca. 8 µm long, spear-like, without projections, only gently narrowing at nearly the mid-length. Club-like sensilla ca. 10 µm long, only on article XIV, grouped on the distal parts of both the internal and external sides. Longitudinal rows of 1-3 propioceptive spine-like sensilla at the bases of the antennal articles: two rows on articles I–III, approximately dorsal and ventral; three rows on articles IV–XIV, approximately dorsal, ventro-internal and ventro-external; rows reduced to 0-1 spine on antennal articles VI, X and XIV. A single sensillum, similar to the apical ones, ca. 5 µm long, on both dorso-external and ventro-internal position, close to the distal margin of articles V, IX and XIII.

First maxillae. Coxosternite entire, without mid-longitudinal sulcus, without setae. Coxal projection sub-triangular, longer than wide, bearing 2 setae. Telopodite apparently composed of a single article, with 1 seta. Lappets apparently lacking.

Second maxillae. Anterior margin of coxosternite concave, without anterior projections. Coxosternite with setae only close to the anterior margin; neither statuminia nor other distinctly sclerotized parts associated to the metameric pores. Telopodite composed of three articles, only slightly narrowing towards the tip, with some distal setae; pretarsus in shape of an elongate claw, more than four times as long as wide at the basis, sub-conic and slightly bent, with a small dorsal bulge.

Forcipular segment. Tergite subtrapezoidal, ca. 2.1 times as wide as long, partially covered both by the cephalic plate and the tergite of the first leg-bearing segment, with lateral margins strongly converging anteriorly, posteriorly ca. 0.8 times as wide as the subsequent tergite. Pleurites with sclerotized scapular ridge. Exposed part of the coxosternite ca. as wide as long; anterior margin slightly projecting anteriorly with intermediate part shallowly concave, with a pair of stout, shallow denticles; coxopleural sutures complete, entirely ventral, straight and subparallel for most of their length; chitin-lines apparently absent. Basal distance between the forcipules ca. 0.1-0.2 of the maximum width of the coxosternite. Forcipular trochanteroprefemur ca. 1.6 times as long as wide, the internal side much shorter than the external side, with two mesal denticles, the distal denticle obviously longer than the basal one and slightly bent basalwards. Forcipular intermediate articles distinct, with a mesal shallow bulge each. Tarsungulum ca. 2.8-2.9 times as long as wide, both the external and the internal profiles uniformly curved, but for a mesal moderate basal bulge bearing two denticles, one dorsal to the other; the dorsal denticle longer than all other denticles and distinctly bent basally, not so the ventral denticle; a groove along the internal side of most part of the ungulum, between a dorsal scalloped ridge and a ventral entire ridge. Poison calyx not elongate, in the forcipular intermediate articles.

Leg-bearing segments. A total of 33 leg-bearing segments. Metatergite 1 slightly wider than the subsequent one, without pretergite. No paratergites. Metasternites longer than wide, without obvious “carpophagus” pit¸ without glandular pore-fields. Legs of the first pair only slightly smaller than the subsequent ones. Leg claws simple, uniformly bent; a pair of accessory spines, shorter than mid-length of the pretarsus, similar to each other in length.

Ultimate leg-bearing segment. Pretergite separated by sulci from pleurites. Metatergite sub-trapezoid, ca. 1.3 times as wide as long, lateral margins convex and distinctly converging posteriorly, posterior margin slightly convex. Metasternite sub-trapezoid, ca. 1.7-1.8 times as wide as long, anteriorly ca. 2.0 times as wide as posteriorly, lateral margins slightly convex and converging backwards; setae distributed uniformly. Coxopleuron ca. 1.7-1.8 times as long of the metasternite; setae distributed uniformly. Coxal organs of each coxopleuron opening through two independent pores, which are approximately aligned along the lateral margin of the metasternite, similar in size, ca. 25-30 µm wide. The telopodite ca. 6-7 times as long as wide, ca. 2.3 times as long and ca. 1.7 times as wide as the penultimate telopodite; six articles, conspicuously swollen, especially prefemur and femur with a disto-ventral bulge each; setae sparse, denser and longer on the ventral distal part of the articles, up to 50 µm long. Pretarsus lacking; a tuft a variously long spines surrounding the tip.

Postpedal segments. Genital pleurosternite entire. Gonopods appearing as a pair of basally wide, short laminae. Anal organs relatively large and anal pores exposed.

Complementary description of mouthparts of another specimen (PD5768)

Labrum. A row of ca. eight very stout tubercles along the posterior margin of the intermediate part. A row of bristles along the posterior margins of the lateral parts.

Mandibles. A single pectinate lamella, with ca. 15-20 teeth, on each mandible.

Intraspecific variability. Considering a total of nine complete specimens, all females with variously developed gonopodal lamina, the body length varied in the range of 5.7-8.1 mm (measured ± 0.1 mm), the maximum width of the cephalic plate varied in the range of 180-235 µm (measured ± 5 µm) and the number of leg-bearing segments was 33 in four specimens and 35 in five specimens. Some variation was found between specimens also in the elongation of antennae (length/width ratio of the longest intermediate article 1.0-1.2; length/width ratio of article XIV 1.8-2.2) and the forcipules (length/width ratio of trochanteroprefemur 1.5-1.7), the shape of the forcipular denticles (denticles on the trochanteroprefemur more or less pronounced and bent; Fig. 1B), the elongation of the metasternite of the ultimate leg-bearing segment (width/length ratio 1.7-2.0) and the shape of gonopodal lamina (either an entire bilobate lamina or apparently two paired laminae).