Colenisia Fauvel, 1903; (Fauvel 1903, Newton 1998, Daffner 1991, Švec 2013)

Body small (0.8-2.5 mm), oval, glossy, usually uniformly brown. Head broad, occipital crest absent, at least half as wide as the pronotum, with distinct microreticulation. Antennal insertion concealed, antennal groove absent. Antennae 11-segmented, relatively compact, 8th antennomere much smaller than 9th and 10th. Labrum not emarginate; mandible with strongly developed molar surface. Elytra with transverse microreticulation. First abdominal segment without a transverse carina. Hind coxae not separated. Tarsal formula 5-4-4 in both sexes. Aedeagus with free parameres.

Length of body 1.25 mm. Maximum width of elytra 0.86 mm. Head width (including the eyes) 0.46 mm. Greatest width of pronotum 0.8 mm. Winged. Short and oval, shiny and sparsely pubescent, dark chestnut, angles of pronotum, strip along suture, and head dark ochre (Fig. 2). Legs and antennomeres I-VI yellow, antennomeres VII-XI orange. Entire dorsum transversely microsculptured.

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b

Figure 2.

Colenisia chungi sp. n., morphology.

a: Female, dorsal view (paratype, BOR/COL/14091)  
b: Female, lateral view (paratype, BOR/COL/14091)  

Head: Ratio of horizontal width of eye (measured in dorsal view and perpendicular to the longitudinal axis of the head) to distance between eyes: 1:7.4. Transverse microsculpture recognisable but too fine to distinguish individual cells at 50x magnification (distance between individual striae is 3-5 µm; Fig. 3a). At 50x magnification, no punctuation is clearly visible. Length of antennomere III 0.8 times the length of antennomere II. Antennomere XI slightly wider than antennomere X (Fig. 5a). Mandible with 16 parallel rows transversely situated on the dorsal molar surface (Fig. 5b).

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c

Figure 3.

Colenisia chungi sp. n., microsculpture.

a: Male, head microsculpture (paratype, FRCS)  
b: Male, pronotum microsculpture (paratype, FRCS)  
c: Male, elytra microsculpture (paratype, FRCS)   

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b

Figure 4.

Colenisia chungi sp. n., aedeagus.

a: Male, aedeagus, dorsal view (drawn after electron micrograph) (paratype, FRCS)  
b: Male, aedeagus, lateral view (paratype, FRCS)  

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b

Figure 5.

Colenisia chungi sp. n., morphology.

a: Male, antenna (drawn after electron micrograph) (paratype, FRCS).  
b: Male, left mandible, dorsal view (tip broken off) (paratype, FRCS)  

Pronotum: Broadest at the base. Base completely straight to posterior angles. Posterior angles form a right angle, while the tip of the angle itself is slightly rounded. From posterior angles to anterior angles, the pronotum is gently curved inwards. The sides and the anterior angle have a fine groove along the entire margin. Transverse microsculpture slightly less distinct than on the head, individual grooves narrowly spaced (3-5 µm apart), but just visible at 50x magnification (Fig. 3b). Punctures (when viewed at 50x magnification) fine and sparse, separated by 5-10 times their own diameter, bearing short, inconspicuous hairs.

Scutellum: Microsculptured as on pronotum.

Elytra: Broadest at basal quarter, roundly curved to apex. Surface with transverse microsculpture. Microsculpture much more pronounced than on the pronotum, already recognisable at 15x magnification. Individual horizontal striae separated from one another by ca. 20 µm (about the width of antennomere III). Punctures separated by around 5-8 times their own diameter, irregularly arranged, each with a hair that can be up to 30 µm long (Fig. 3c). Sutural stria absent.

Legs: Anterior tarsomeres I-IV not markedly widened in the male.

Aedeagus: Median lobe elongated, parallel-sided, at the tip extended into a flat processus reminiscent of a duck-bill. Parameres thin, short, two-thirds of the length of the median lobe, slightly widened at the tip and provided with two long hairs, each about one-third of the length of the paramere itself (Fig. 4a). In lateral view, the median lobe is gently curved and apically flattened into a wedge (Fig. 4b).

Spermatheca: A near-spherical bulb with a tube about twice as long as the diameter of the bulb and about a third of its diameter. Tube from its base narrowing to about half its own diameter towards the terminus.

The eye size, dorsal microsculpture, shape of aedeagus and antenna, as well as the presence of irregularly arranged punctuation on the elytra, place this species near C. championi (Portevin 1937) from South India, C. pecki Daffner 1988 from Japan and C. castanea Švec 2011 from China. However, C. championi has longer parameres and a less clearly sinuous outline of the aedeagus apex (Daffner 1991). C. pecki has the 11th antennomere much smaller than in C. chungi. C. castanea has acute posterior angles of the pronotum and a more stocky aedeagus (Švec 2011).

Named in honour of Dr. Arthur Y. C. Chung, who collected the first known specimen in 2005.

Known only from two locations in the valley where the Maliau river flows out of Maliau Basin, located at 290 m elevation (Maliau Basin Studies Centre) and 670 m elevation (Ginseng Camp).

Only collected from leaf litter on the forest floor in lowland dipterocarp tropical rainforest. The two specimens from the Maliau Basin Studies Centre were both collected from between buttress roots, whereas leaf litter from the forest floor yielded no specimens. Perhaps this is an indication of its preferred microhabitat.

Dermatohomoeus Hlisnikovský, 1963 (Hlisnikovský 1963, Daffner 1986, Newton 1998)

Body convex, shiny, brown. Head without any microreticulation but with punctate microsculpture, occipital crest absent, antennal insertion concealed, antennal groove absent, labrum not emarginate. Antenna slender, 11-segmented, 8th antennomere much smaller than 9th and 10th. Mandible with clear molar surface. Pronotum more than twice as wide as the head, with fine and densely placed punctures. Elytra with densely placed punctures and transverse microsculpture. Mesosternum with longitudinal carina. First abdominal sternite without a transverse carina. Hind coxae not separated. Tarsal formula 5-4-4 in males and females. Aedeagus with free parameres.

Length of body c. 1.4 mm (Fig. 6). Oval, 1.45x longer than wide, greatest width at the shoulders. Pronotum 2.0x wider than the head. Winged. Reddish brown, with yellow legs and antennae. Eyes large. Antennae slender, antennomere VII 1.5x as long as wide. Pronotal posterior angle not drawn out, only a very faint convex curve next to the rounded angles. Elytra sparsely pubescent, with distinct punctuation, here and there arranged into longitudinal rows. All punctures on the elytra connected by microreticulation.

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Figure 6.

Dermatohomoeus maliauensis sp. n., habitus.

a: Female, dorsal view (paratype, BOR/COL/14093)  
b: Female, lateral view (paratype, BOR/COL/14093)  

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Figure 7.

Dermatohomoeus maliauensis sp. n., microsculpture.

a: Male, head microsculpture (paratype, FRCS)  
b: Male, pronotum microsculpture (paratype, FRCS)  
c: Male, elytra microsculpture (paratype, FRCS)  

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b

Figure 8.

Dermatohomoeus maliauensis sp. n., aedeagus.

a: Male, aedeagus, dorsal view (paratype, FRCS)  
b: Male, aedeagus, lateral view (paratype, FRCS)  

Head: Eyes large, each with an estimated 40-50 ommatidia. Ratio of horizontal width of eye (measured in dorsal view and perpendicular to the longitudinal axis of the head) to distance between eyes: 1:4.4. A thin supraorbicular groove runs along the inner margin of the eyes and over the antennal insertion. Length of antennomere III 0.7 times the length of antennomere II. Antennomere IX slightly narrower than antennomere X. Antennomeres X and XI of equal width (Fig. 9). Punctuation (when viewed at 50x magnification) distinct, individual punctures spaced by 3-5 times their diameter (Fig. 7a). No microreticulation visible.

Figure 9.  

Dermatohomoeus maliauensis sp. n., male, antenna (drawn after electron micrograph) (paratype, FRCS)

Pronotum: Broadest at the base. Pronotal posterior angle rounded, not drawn out, the pronotal basis near the posterior angle with only a very faint convex curve. Pronotum smooth, glossy, hairless, without any microreticulation but with very fine and sparse punctuation, punctures spaced at 3-5 times their diameter, nearly invisible at 50x magnification (Fig. 7b). A fine, continuous margin runs along the lateral and anterior margin.

Scutellum: Microsculptured as on pronotum.

Elytra: Broadest at the shoulders, roundly curved to apex. Elytra with distinct punctuation. Punctures separated by ca. 3x their own diameter, here and there arranged into longitudinal rows. All punctures connected by jagged horizontal striae that are spaced ca. 20 µm apart. Elytra with sparse hairs emerging from the punctures; these hairs are short, about as long as the width of antennomere III (Fig. 7c).

Aedeagus: Median lobe in dorsal view gradually narrowing towards the apex, terminally shaped into a broad, mushroom-shaped plate that is twice as wide as long (Fig. 8a). The apical angles of the ventral piece can be seen emerging on either side of this plate. Parameres reach the level of the basis of this plate. The dorsal surface of the terminal one-third of the median lobe is covered in coarse granules (only visible with scanning electron microscopy). In lateral view (Fig. 8b), the median lobe is basally strongly curved ventrad, but in the terminal one-third curved gently dorsad and flattened into the shape of a thin wedge.

Spermatheca: Not studied.

As pointed out by Švec (2009), Dermatohomoeus species are often very similar externally and the male genitalia offer the only certain identification. The shape of the aedeagus separates D. maliauensis sp. n. from nearly all Dermatohomoeus species for which the male genitalia are known. One species with similar male genitalia is the widespread D. portevini (Champion, 1923). The size of the body and eyes, the microsculpture of the dorsum, and the shape of the pronotum indeed place the new species in the close vicinity of D. portevini. However, in D. portevini the median lobe of the aedeagus displays a bulge directly basal of the terminal plate (Daffner 1988), which is not the case in D. maliauensis sp. n. Also, the 7th antennomere is broader in D. maliauensis. A second species with a similar aedeagus is D. bidentatus Švec & Cooter 2015 from Yunnan, China which, however, is characterised by the two lateral teeth at the terminus of the median lobe; moreover, it is nearly twice as large (Švec and Cooter 2016). Another species that appears to possess similar external characteristics is D. terrenus (Hisamatsu 1985) from Korea and Japan. This species is thought to be parthenogenetic, as no males are known (Park and Ahn 2007). D. terrenus differs from D. maliauensis sp. n. in having an 11th antennomere that is distinctly broader than the 10th and by transverse microsculpture on the pronotum, which is absent in D. maliauensis sp. n.

Named after Maliau Basin Conservation Area in Sabah, Malaysian Borneo. This 30-km-wide circular depression, covered with montane forest on poor soils and surrounded by steep sandstone cliffs, is known as "Sabah's Lost World". It is the focal area for the Borneo work of Taxon Expeditions. The species epithet was selected during a naming ceremony in Maliau Basin Studies Centre on 6 October 2017, in which expedition participants as well as a large number of field centre staff and porters took part. As far as the authors are aware, this is the third animal species named for this under-explored area (Disney 2016, Buhl 2009).

Known only from two locations in the valley where the Maliau river flows out of Maliau Basin, located at 260 m elevation (Maliau Basin Studies Centre) and 670 m elevation (Ginseng Camp).

Clavicornaltica Scherer, 1974; (Medvedev 1996, Scherer 1974, Konstantinov and Duckett 2005)

Small (0.7-2.2 mm), convex flea beetles, with strongly developed jumping hind legs and characteristically clavate antennae. Frons is broad, antennal insertions widely separated. Antennae 11-segmented, clavate after the 3rd antennomere. The first three antennomeres are long and slender, the next three very small, the final five are enlarged and form a club. Pronotum with two setal pores, the anterior of which is placed behind the middle of the lateral margin. Metasternum with an anterior-pointing, broad processus. Posterior femora strongly dilated. Metatibia slender and with a long terminal spore and a row of smaller terminal setae on the lateral edge.

Body dark reddish brown, small, oval and convex, ca. 0.75 mm long and ca. 0.58 mm wide (Fig. 10a). Eyes ca. 1/7 the width of the head. Antennae yellowish brown; clava long and moderately robust. Female wingless. Tibia and tarsus yellowish brown, femur dark brown and robust. Male unknown.

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Figure 10.

Clavicornaltica sabahensis sp. n., female morphology (holotype, BOR/COL/14089).

a: Habitus lateral view  
b: Habitus frontal view  

Head (Fig. 10b): Rectangular, shallowly and sparsely punctate; vertex smooth; frontal tubercles present, frontal carina absent. Eyes ca. 1/7 the width of the head in dorsal view. Antennae: clava long and moderately robust (Fig. 11).

Figure 11.  

Clavicornaltica sabahensis sp. n., female, antenna (holotype, BOR/COL/14089).

Pronotum: Lenticular in dorsal view, convex, four angles angular with a deep furrow along the length of the edge, which itself is somewhat angular in the middle with two deep seta-bearing pores: one at ¼ of the margin’s length, the other in the posterior angle. Punctuation covers the entire surface in an irregular pattern and is the same strength as the dorsal surface of the elytra.

Hind wings: Absent.

Elytra: Striae punctiform, punctures shallower dorsally, more deeply impressed laterally and becoming less visible towards the very apex. A deep but narrow punctuated groove runs along the entire margin continuing to the apex; apex itself slightly drawn out.

Legs: Metafemur robust, oval, covered in fine white setae. Metatibia bearing eight minute setae which cover the terminal one-quarter along the external edge and one long spine, slightly shorter than the first tarsomere, provided with three minute teeth (Fig. 12).

Figure 12.  

Clavicornaltica sabahensis sp. n., female, hind leg (holotype, BOR/COL/14089).

Abdomen: Carina on the first abdominal sternite sharp and narrow.

Differential comparisons were made with all known species of the genus. Clavicornaltica sabahensis sp. n. differs from these in the following respects. Clavicornaltica buechei Medvedev, 2008 (Sulawesi): is larger (1.4 mm) and the ridge on the first abdominal segment is widened posteriorly (Medvedev 2008). Clavicornaltica mizusawai Suenaga & Yoshida, 2016 (Taiwan) has impunctate elytra and larger eyes (Suenaga and Yoshida 2016). Clavicornaltica sakishimana Suenaga & Yoshida, 2016 (Japan) has the carina on the first abdominal sternite widened caudally (Suenaga and Yoshida 2016). Clavicornaltica pusilla Scherer, 1974 and C. loebli Scherer, 1974 (Sri Lanka) have impunctate elytra (Scherer 1974). C. besucheti Scherer, 1974 (Sri Lanka) is larger, 1.5-2.2 mm (Scherer 1974). Clavicornaltica malayana Medvedev, 1996 (Malaysia) has the pronotum impunctate (Medvedev 1996). Clavicornaltica iriana iriana Medvedev, 1996 (New Guinea) is larger (1.2-1.4 mm), has larger eyes, only 4-5 rows of punctures on the elytra and these do not continue to the apex (Medvedev 1996). Clavicornaltica iriana sarawacensis Medvedev, 1996 (Borneo) is larger (1.2-1.4 mm) and the elytral punctures are only visible laterally (Medvedev 1996). Clavicornaltica takizawai Doeberl, 2009 (Nepal) is larger (1.45 mm) and its frons and vertex are densely punctuated (Döberl 2009). Clavicornaltica mussardi Scherer 1974 (Sri Lanka) is larger (1.3-1.5 mm) (Scherer 1974). Clavicornaltica rileyi Döberl, 2002 (India) is larger (1.5 mm) and its eyes are larger (Döberl 2002). Clavicornaltica dali Konstantinov & Duckett, 2005 (Yunnan): punctures on the head are stronger and those on the pronotum weaker than in C. sabahensis sp. n. (Konstantinov and Duckett 2005). Clavicornaltica tarsalis Medvedev, 1996 (Irian Jaya) is larger, 1.6 mm and the ridge on the first abdominal sternite is anteriorly broadly widened (Medvedev 1996). Clavicornaltica australis Konstantinov, 1996 (Queensland) lacks the long seta in the middle of the pronotal edge (Konstantinov and Duckett 2005). Clavicornaltica fortepunctata Scherer, 1974 (Sri Lanka): elytral punctuation fades abruptly before the apex (Scherer 1974). Clavicornaltica trautneri Medvedev, 1993 (Philippines) is much larger (2.1 mm) (Medvedev 1996). Clavicornaltica takimotoi Lesage, 1997 (Taiwan) is more globular and the punctures on the dorsum of the elytra are nearly invisible (Suenaga and Yoshida 2016). Clavicornaltica philippinensis Scherer, 1979 (Philippines) is larger (1.3 mm) (Medvedev 1996). Clavicornaltica tamdao Konstantinov & Duckett, 2005 (Vietnam): terminal setae on the metatibia are more numerous (12 in C. tamdao versus 8 in C. sabahensis sp. n.) and cover a larger section of the tibia (the terminal one third) (Konstantinov and Duckett 2005). Clavicornaltica vietnamensis Konstantinov & Duckett, 2005 (Vietnam): apex of the elytra is less extended (Konstantinov and Duckett 2005).

Since this is the first species of Clavicornaltica found in Sabah, the specific epithet sabahensis ("inhabitant of Sabah") was chosen. This was one of several names suggested during a naming ceremony in Maliau Basin Studies Centre on 6 October 2017, in which expedition participants as well as a large number of field centre staff and porters took part.

Known only from one location in the valley where the Maliau river flows out of Maliau Basin, at 260 m elevation (Maliau Basin Studies Centre).

Only a single female was at the authors' disposal. Nonetheless, the authors felt confident that this specimen represents an undescribed species. First of all, given their small size, apterism/brachypterism, and habitat (leaf litter in forests), it is unlikely that Clavicornaltica species have wide ranges (Konstantinov and Duckett 2005) and the only species known from Borneo and its immediate vicinity have external characters that do not match C. sabahensis sp. n. (see under Diagnosis). Moreover, C. sabahensis sp. n. carries a combination of traits that make it easily recognisable. Specifically, these are its extremely small size, highly vaulted shape, dark colouration, narrow ridge on the first abdominal sternite, angular, thick pronotal margin, and strong punctuation on the entire elytra.