Monodontocerus mulunensis, Yu, Daoyuan, Deharveng, Louis & Zhang, Feng, 2014

Yu, Daoyuan, Deharveng, Louis & Zhang, Feng, 2014, New species of Monodontocerus (Collembola: Tomoceridae) from southern China with diagnostic notes on the genus and introduction of new taxonomic characters, Zootaxa 3768 (5), pp. 557-575 : 565-568

Monodontocerus mulunensis sp. nov.

Figs 4 , 30–40 , 55, 58 , Table 2

Type material. Holotype female and three paratype females on slides, four paratypes in alcohol, collected in Gou Yu Dong cave, Hongdong Village, Mulun Township, Huanjiang Autonomous County, Hechi, Guangxi Zhuang Autonomous Region, China, x= 107.969942°E; y= 25.146986°N; elevation 583 m, 27.vi.2011, by Youbang Li, Zheng Tang and Shiyi Lu (sample code: CHIgx11-LYB09). Holotype, two paratype on slide and two paratypes in alcohol in NJAU, one paratype on slide and two paratypes in alcohol in MNHN.

Description. Body length 3.5–4.0 mm. Color pale without trace of pigment except the small black eye patches ( Fig. 4 ).

Postantennal organ absent. Ommatidia 6+6, small. Antennae about 0.65 times length of body, antennal length ratio as I: II: III: IV= 1.0: 1.5: 5.9: 1.1. Ant. I and Ant. II dorsally scaled, base of Ant. III dorsally with a few scales; ventral side of Ant. I and Ant. II with more s-chaetae than dorsal side; Ant. III and IV annulated, each subsegment near the middle of Ant. III with a whorl of 25–30 chaetae. Types of chaetae on Ant. III and Ant. IV similar to those of M. absens sp. nov., but type c not seen.

Mouthparts similar to those of other species in the genus. Labral formula 4/5, 5, 4, with four distal papillae. Left mandible head with four teeth, right mandible with five teeth; molar plate with one tapered distal tooth ( Fig. 30 ). Maxilla head with three teeth and six lamellae, lamella 5 with long basal teeth but no beard ( Fig. 31 ). Maxillary outer lobe with trifurcate palp, one basal chaeta and four sublobal hairs. Labium not clearly observed.

Head dorsally scaled, macrochaetotaxy: anterior 2, 2; interocular 2, 3 (including axial chaeta); postocular 2+2; posterior. Numerous microchaetae uniformly distributed; posterior margin with about 35 small smooth chaetae in complete row ( Fig. 55 ). Head ventrally with numerous scales and smooth chaetae of different sizes.

Trochanteral-femoral organ with 1, 1 slender larger chaetae and several smaller additional chaetae on trochanter. Femora with several long outstanding chaetae on inner side. Tibiotarsi with 0, 0, 2 blunt spine-like inner chaetae ( Fig. 32 ), distal whorl with 11 chaetae, dorsal group with one slender, smooth, pointed tenent hair, 1+1 small accessory chaetae and 1+1 outer chaetae similar to but longer than tenent hair ( Figs 33, 34 ). Unguis rather slender, outer edge 0.33, 0.30, 0.20 times length of fore, middle, and hind tibiotarsi respectively ( Fig. 32 ), basolaterally with internal ridging; lateral teeth pointed; inner side of unguis with 5–6 teeth, the subbasal tooth the strongest. Unguiculus slender, two-thirds length of inner edge of unguis, with 1–4 inner teeth ( Fig. 35 ). Pretarsus with 1+1 microchaetae.

Ventral tube scaled on both anterior and posterior sides, each side of anterior face with 50–70 chaetae, posterior face with about 130 chaetae; lateral flap unscaled, each side with about 70 chaetae. Rami of tenaculum with 4+4 teeth, corpus unscaled, with one anterior chaeta ( Fig. 36 ). All chaetae on ventral tube and tenaculum smooth, pointed.

Furca 0.56 times length of body, ratio manubrium: dens: mucro as 3.6–3.8: 5.0–5.5: 1.0. Manubrial width: length = 0.5, ventrally scaled, laterally with large round scales and a row of about 10–12 chaetae, distal chaetae strong and serrated. Each dorsal chaetae stripe on manubrium with about 240 smooth chaetae of various sizes mixed with numerous scales; external to the stripe a longitudinal row of 20–26 pseudopores ( Fig. 37 ), single externo-distal chaeta same length as a mesochaeta in the chaetal stripe ( Fig. 38 ).

Length ratio of three parts of dens as 1.0: 1.4: 3.4 from basal to distal. Dental spine formula 6/5–6, I, 3, I in a single row. Dental spines with 2–6 denticles. Largest dental spines about 0.08 times length of dens ( Fig. 39 ). Dens dorsally with three types of chaetae as usual for the genus, ventrally covered by oval scales without chaetae. Mucro elongated with numerous smooth chaetae and two dorsal lamellae; single basal tooth with one proximal lamella; intermediate teeth 3–5, unequal, the subdistal tooth the smallest; apical tooth stronger than subapical tooth, with hooked apex ( Fig. 40 ).

General pattern of tergal macrochaetae and large mesochaetae similar to that of M. absens sp. nov. Number of macrochaetae in posterior row from Th. II to Abd. V 3, 3, 3, 3, 3, 2, 4; two anterior macrochaetae on Abd. III subequal in size; external posterior macrochaeta of Abd. III and external anterior macrochaeta on Abd. IV reduced to mesochaeta size; on Abd. V, macrochaeta p3 larger than others and located more anteriorly; seven macrochaetae present on dorsal flap of Abd. VI ( Fig. 58 ). Pattern of bothriotricha as 2, 1/ 0, 0, 1, 2, 0, 0 from Th. II to Abd. VI. Mesochaetae of various sizes. Microchaetae uniformly distributed. Observed s-chaetotaxy as follows: on Th. II, three s-chaetae close to bothriotricha, the antero-inner one as rod-like s-chaeta, the external one as s-microchaeta and the middle one as normal s-chaeta, another normal s-chaeta present posteriorly close to a small chaeta. On Abd. III, one s-microchaeta posterior to antero-external macrochaeta; on Abd. IV, long s-chaetae present near middle line, their number uncertain due to shedding (at least 5 remaining in one paratype).

Pseudopores near the middle of terga, 1, 1/1, 1, 1, 1, 0, 0 on each side from Th. II to Abd. VI ( Fig. 58 ). On Th. II pseudopore close to the posterior macrochaeta of the three antero-median chaetal group; on Abd. I, pseudopore located more posteriorly than on other terga.

Etymology. Named after the National Reserve of Mulun where the species was found.

Remarks. Monodontocerus mulunensis sp. nov. is recognizable by a combination of characters of chaetotaxy, foot complex and furca ( Table 2 ). It has 2, 3 interocular macrochaetae, which is different from the 2, 5 pattern in the three previously described species M. modificatus , M. odongnyeoensis and M. leqingensis. From the two other new species, it differs mainly in the number of posterior macrochaetae on Abd. III (three versus four) and the number of mucronal intermediate teeth (3–5 versus two), besides, its tibiotarsal spine-like chaetae are stronger than those of Monodontocerus absens sp. nov. and Monodontocerus trigrandis sp. nov.

Figures

FIGURES 1 – 5. 1 – 3, Monodontocerus absens sp. nov. 1, habitus; 2, spotted pigmentation on Abd. III; 3, head, arrows pointing to the pigmented sockets of cephalic posterior macrochaetae; 4, habitus of M. mulunensis sp. nov.; 5, habitus of M. trigrandis sp. nov. Scale bar: 1, 200 Μm; 2, 3, 25 Μm; 4, 5, 100 Μm.

FIGURES 30 – 36. Monodontocerus mulunensis sp. nov.: 30, mandible; 31, maxillary lamella 5; 32, tibiotarsus; 33, tibiotarsal distal chaetae; 34, pattern of tibiotarsal distal chaetae (distal view); 35, claw; 36, tenaculum. Scale bar: 30, 33, 35, 36, 50 Μm; 31, 20 Μm; 32, 200 Μm.

FIGURES 37 – 40. Monodontocerus mulunensis sp. nov.: 37, manubrium (circle with a slash: pseudopore); 38, disto-external corner of manubrium and corner chaeta; 39, dental spines; 40, mucro. Scale bar: 37, 39, 40, 100 Μm; 38, 50 Μm.

FIGURES 54 – 59. Dorsal cephalic and body chaetotaxy: 54 & 57, M. absens sp. nov.; 55 & 58, M. mulunensis sp. nov.; 56 & 59, M. trigrandis sp. nov. Large circle: macrochaeta; small circle: mesochaeta; wavy line: bothriotricha; s: normal s-chaeta; ms: s-microchaeta; rs: rod-like s-chaeta on body; circle with a slash: pseudopore.