Monographis cattienensis, Huynh, 2022

Huynh, Cuong, 2022, Four new species of Monographis Attems, 1907 (Diplopoda, Polyxenida, Polyxenidae) from Vietnam, Zootaxa 5214 (3), pp. 393-420 : 397-403

Monographis cattienensis new species

Figures 3–7

Material examined: Type specimens. Holotype adult male, to be returned to the Zoological Museum of the Moscow University ( ZMUM), Moscow, Russia . Paratypes, 2 males and 2 females ( ZMUM), all collected from the study of microarthropods and macrofauna in the Nam Cat Tien National Park during 2004–2005 (Anchkin et. al., 2007), a south-eastern lowland forest, Dong Nai Province, Vietnam ; 11.4475N, 107.442778E, elevation 131 m. Specimens were sent to authors by Professor Sergei Golovatch, the collections were preserved in 80% ethanol, the specimens appeared brownish in colour, and most trichomes and antennae were lost.

Diagnosis: Body length 2.6–3.6 mm. Antennal article VI with 14–16 bacilliform sensilla forming crescent shape, setiform sensillum located anterior position, conical sensillum present near centre of crescent. Labrum setose, with long slender anterior setae on anterior margin. Telotarsus with posterior lateral process less than half length of claw, anterior lateral and lamella processes present, anterior setiform process longer than claw.

Description:

Holotype male body 2.6 mm; paratypes: males 2.6–2.8 mm, females 3.4–3.6 mm; caudal bundle in both sexes same length 0.5 mm, nest trichomes in female 0.2 mm.

Head: Each side 8 ommatidia: 4 dorsal, 4 lateral (1 anterior, 2 medial and 1 posterior). Vertex with 2 posterior trichome groups (pv) and a large medial gap. Each group with 2 rows: Anterior row curved slightly, on an oblique angle with large trichome sockets in central position, gradually reducing the size at both ends (holotype 12 each side); posterior row with few small sockets (holotype 2 each side); a narrow space between these rows. ( Figures 3A & 3B ). Paratypes showed that variation is common in this species, regardless of sex, ranging from 12–16 sockets in anterior rows, 2–3 in posterior rows. Trichobothria: typically thin, sensory hairs with narrow cylindrical funicles; trichobothria equal in socket size forming an isosceles triangle with equal distance ab and bc, trichobothrium a located in interior position, trichobothrium b in lateral position, trichobothrium c in exterior position of the head capsule ( Figures. 3A & 3C ). Gnathochilarium: Lateral palp 1.25 times medial palp; 11 conical sensilla on the lateral palp and 22 on the medial palp, same in holotype and paratypes ( Figure 3D ). Clypeo-labrum: Holotype, labrum posterior margin with 12 setae (Se), setae equal in length to labrum width; Paratypes, 10–12 setae in both sexes. Labrum surface setose (l), labrum posterior margin has a row of minute backward-pointing setae (sb). Lateral lamella (Ll) and single broad lamella each side of median cleft (mc); 7 (Left: L) and 12 (Right: R) slender setae (sa) present on anterior margin of labrum. The number of these anterior slender setae varies among paratypes, ranging from 18–20 across both sides. ( Figure 3E ).

Antennae: Antennal article VI with 15–16 bacilliform sensilla. Holotype with 16 bacilliform sensilla forming a crescent shape with 3 thick ( T) and 8 thin bacilliform sensilla (t), 5 short thin bacilliform sensilla (ts); setiform sensillum (S) located in anterior position, conical sensillum (C) present near the centre of the crescent ( Figures 4C , 7B & 7C ). Antennal article VII with 2 thick bacilliform sensilla ( T, Ta and Tp), setiform sensillum (S) located in between these two sensilla ( T), conical sensillum (C) located next to Tp ( Figure 4B ), which is an arrangement typical of the genus.

Body. Collum—the first tergite with a pair of pleural projections called lateral protuberances (Lp) ( Figure 5A ); tergites 2 (T2) to 10 (T10), each connected with a pair of pleural projections (pp) ( Figure 5B ); tergite T10—the last tergite, trichome sockets dense and smaller ( Figure 5C ).

Legs. Leg segmentation following Manton (1956) and with articles typical of Polyxenida : legs 1 and 2 without trochanter, leg 1 without tarsus 1. Chaetotaxy (setae on leg articles): coxa 1 and 2: 2 setae, coxae 3–13: 2–4 setae; pre-femur, post-femur, tibia with 1 seta, except femur with 1–4 setae, tarsus 1 and 2 with a spine. Coxa, pre-femur and femur with biarticulated seta and ridged funicle. 1–3 smaller biarticulated setae in posterior position of femur, some also on penis. Post-femur and tibia distally with setiform seta. The spine on tarsus 2 is sharply pointed and twice the length of a spine in the antero-sternal position of tarsus 1 ( Figures 6A–C , 7E , 10A , 12C , 15A , 20A & 23C ).

Telotarsus: Claw slender with anterior lateral (a) and posterior lateral (p) processes less than half length of the claw (c); the anterior setiform process (s) is longer than the claw; lamella process (la) is present ( Figures 6D & 7F ).

Sex organs in the male: A pair of penes on coxae 2 and 2 pairs of coxal glands are located on the 8th–9th coxal plates ( Figures 6E & 22B ).

Caudal bundles: Similar to congeners ( Huynh & Veenstra 2020) and classified as caudal bundle type I arrangement ( Condé & Nguyen Duy-Jacquemin, 2008). Caudal trichomes with a series of 2–6 backward hooks ( Huynh & Veenstra 2013) ( Figures 12B , 23A & 23B ).

Telson: Dorsal ornamental trichome sockets symmetrically arranged either side of telson; 17 (L) and 18 (R) sockets of trichomes a on each side of the telson in the holotype (paratypes with 16–18). Trichome a sockets form 2 rows, top row with small sockets, bottom row with larger sockets. Socket of trichome b and 3 large sockets trichomes c with protruding base: c1, c2 and c3, forming triangular shape located in ventroposterior positions in each arrangement. Circular indentation d apparent each side near the exterior side of trichomes c ( Figure 6F ).

Remarks: Monographis cattienensis sp. n., differs from other species in the genus in several characters. It has a distinctive number of bacilliform sensilla arranged in a crescent shape, setose labrum surface and slender setae present on lamellae along the anterior margin of the labrum, plus an anterior setiform process longer than the claw.

Etymology: Monographis cattienensis is named after the Cat Tien National Park in Dong Nai Province, Vietnam, where this species was collected.

Figures

FIGURE 3. Holotype male Monographis cattienensis sp. n.. A. The head capsule showing eye patterns (each side with eight ommatidia); trichobothria: trichobothrium a, b and c; anterior vertex (av) and posterior vertex (pv). B. The enlarge trichome sockets in posterior vertex, pv (L): left side, pv (R): right side. C. Trichobothria (left side): trichobothrium a (interior position), b (lateral) and c (exterior); D. Right gnathochilarium showing lateral palp (Lp) with 11 conical sensilla and medial palp (Mp) with 22; E. Clypeo-labrum showing setose surface, with two lateral lamellae (Ll), two lamellae (l) and a median cleft (mc), anterior setae (sa); posterior setae (Se); a row of backward-pointing setae (sb).

FIGURE 4. Holotype male Monographis cattienensis sp. n.. A. Antennal articles VI, VII, VIII and sensory cones (sc); B. and C. showing the arrangements of sensilla on articles VI and VII. (T: thick bacilliform sensillum (Ta: anterior, Tp: posterior position), t: thin bacilliform sensillum, ts: short thin bacilliform sensillum, S: setiform and C: conical sensillum)

FIGURE 5. Holotype male Monographis cattienensis sp. n. with typical trichome socket patterns on the collum and tergites of Monographis species. A. Collum (Col)—the first tergite showing trichome patterns and the first pair of pleural projections—lateral protuberances (Lp); B. Trichome socket patterns present on tergites 2 (T2) to 9 (T9), and pleural projections (pp); C. Trichome socket patterns present on tergite 10 (T10)—the last tergite, and its pleural projections, the trichome sockets showing dense and smaller than other tergite.

FIGURE 6. Holotype male Monographis cattienensis sp. n.. A. The second leg showing the segments and the chaetotaxy— hairs on its segments: Coxa (co), prefemur (pf), femur (f), postfemur (pof), tibia (tib), tarsus 1 (T1), tarsus 2 (T2) and claw (c); B. Typical seta present on leg articles; C. Spine on Tarsus 1 & 2; D. Telotarsus: Claw (c), lamella (la), setiform (s) and anterior (a), posterior (p) lateral processes. E. Two pairs of coxal glands present on coxae VIII and IX; F. Dorsal ornamental trichome sockets showing both sides, trichome sockets a: a1 to a18 (Left), with 17 sockets (Right); trichome socket b; trichome sockets c: c1, c2 and c3. Circular indentation d; G. Female’s nest trichome; H. A caudal bundle trichome.

FIGURE 7. SEM images of Monographis cattienensis sp. n.. A. antennal articles VI, VII and VIII; B. and C. showing the arrangement of sensilla on the article VI; D. Clypeo-labrum showing setose surface with anterior setae (sa), lateral lamella (Ll), median cleft (mc), row of backward-pointing setae (sb) and posterior setae (Se); E. Leg articles and two spines (pointed arrows) which are typical characters of Monographis; F. Telotarsus showing processes: anterior lateral process (a), posterior lateral process (p), claw (c), anterior setiform process (s) and lamella (la).

FIGURE 10. Holotype female Monographis konkakinhensis sp. n.. A. The second leg showing its segments and its chaetotaxy, vulva (v); B. Telotarsus and its processes, dotted line indicating setiform (s) shorter than the claw (c); C. Dorsal ornamental trichome sockets showing both sides with 25 sockets a, one b, three c (c1, c2 & c3) and the indentation d on each side.

FIGURE 12. SEM images of a female Monographis konkakinhensis sp. n.. A. The vulvae (v) in coxae II; B. Telson (Te) showing the ornamental trichome sockets (ots) dorsally, trichome bundle structures with the main caudal barbate trichome sockets (cbts), few barbate trichome sockets (bts) in the centre of the bundle, two bundles of nest trichome sockets (nts) ventrally; C. Leg segments and two spines (pointed arrows) typical Monographis; D. Telotarsus and its processes (a: anterior lateral process, p: posterior lateral process, c: claw, s: anterior setiform process, la; lamella process).

FIGURE 15. Holotype male Monographis tamdaoensis sp. n.. A. The second leg showing its segments and chaetotaxy, penis (p). B. Telotarsus showing the claw (c) and processes: anterior (a), posterior (p), lamella (la) and anterior setiform process (s) shorter than half length of the claw (dot line). C. The ornamental trichome sockets with trichomes a, b, three c and an indented d.

FIGURE 20. Holotype male Monographis thatsonensis sp. n.. A. Second leg showing seven articles: coxa (co), prefemur (pf), femur (f), postfemur (pof), tibia (tib), tarsus 1 (T1), tarsus 2 (T2); claw (c) and penis (p). B. Telotarsus showing claw (c) and all processes: anterior (a), posterior (p), setiform (s) and the lamella (la). C. Ornamental trichome sockets showing the arrangements on both sides: trichome sockets a, b, c, and indentation d.

FIGURE 22. SEM images of Monographis thatsonensis sp. n.. A. The head—right side showing the posterior vertex (pv) trichome sockets and trichobothria (a, b, and c). B. Coxal glands on legs VIII and IX (pointed arrows). C. Clypeo-labrum showing structure of labrum (l) with asetose surface, lateral labrum (Ll), medial cleft (mc), anterior setae (sa), posterior setae (Se), backward-pointing setae (sb). D. Gnathochilaria (g): lateral palps (Lp) and median palps (Mp), the frons (f), labrum (l).

FIGURE 23. SEM images of Monographis thatsonensis sp. n.. A. Male’s caudal bundle with ornamental trichome sockets (ots) a, b, c and d; and telson (Te), and the bundle with caudal bundle trichome sockets (cbts), barbate trichome sockets (bts); the last pleural projection (pp). B. Female’s caudal bundle structure showing the same dorsally, except the presence of two bundles of nest trichome sockets ventrally (nts). C. Presence of two spines—Tarsus 1 and 2, typical of Monographis species. D. Telotarsus showing a claw (c) and all processes: anterior (a), posterior (p), anterior setiform process (s) and lamella (la).