Trachusa tenebrosa, Kasparek, 2019

Kasparek, Max, 2019, A new species in the Trachusa ovata species group (Hymenoptera: Apoidea) from Peninsular Malaysia with an overview of the old-world species within the genus Trachusa, Journal of Natural History 53 (17), pp. 1079-1094 : 1082-1089

Trachusa tenebrosa sp. nov.

( Figures 1 – 8 )

Material

Holotype, female. MALAYSIA: Johor: Kluang District: Mount Lambak ( Gunung Lambak ) (02° 01 ʹ N, 103°21 ʹ E), 05.v. 1971, C. G. Roche leg. Fresh specimen with unworn mandibles and intact wing tips. – Labels on type specimen (different labels separated by slashes ” / ”): ‘Protanthidium sp. aff. ovatum Cam. , det. D. B. 1982 compared with type ov./9804/ D&M Baker Collection KUNHM 2004 -En-004/ROCHE/ SEMC0974792 KUNHM-Ent/ MALAYSIA (Johore) G. Lambak 8.5.1971 C. G. Roche / Trachusa rufobalteatum [sic!] ♀ det. T. Griswold ’). – Note: The specimen is deposited in the Donald and Madge Baker collection which is not the usual SEMC material (see Engel and Dathe 2009).

Description (female)

14 mm. colouration: Ground colouration dark reddish brown to black. Yellow markings entirely absent ( Figure 1 ). – Head: Clypeus slightly convex, apical margin shallowly emarginate ( Figure 5 ); on dorsal margin slightly yet distinctly incurved above anterior tentorial pits; apical emargination weakly crenulate with tufts of short light brown hair; punctation of clypeus dense with much finer punctures in apical area; punctures hexagonal; middle line sparsely punctured, slightly carinate. Mandible strong, broad at apex; big, blunt apical tooth and anterior edentate ridge with four, hardly distinguishable teeth (tooth ridge) ( Figures 4 – 5 ). Subantennal suture inconspicuous, slightly outwardly arcuate; dorsal surface of antenna dark brown, light reddish brown ventrally; entire head with dense punctation excepting supraclypeal area where, in an extension of the clypeal median carina, a sparsely punctured central line is found. Posterior part of head well-developed, lateral ocellus nearer to the eye than to preoccipital margin (distance to eye 0.74 mm, to preoccipital ridge 0.89 mm). Interocellar distance (0.54 mm) less than ocelloccipital distance (0.89 mm) ( Table 1 ). Preoccipital ridge rounded. Head with short erect yellow-brown to red-brown pubescence, slightly longer hair between and around antennal sockets. Maxillary palpus three-segmented with broad basal segment and two equally long distal segments. – Wings: Light brown infuscated, anterior part (mainly radial cell and first cubital cell) somewhat more strongly than the posterior area ( Figure 6 ) (Note: visibility of wing pattern strongly affected by way wing is displayed against various backgrounds with different lighting properties). Vein cu-v of hind wing oblique, approximately 82% of the length of the second abscissa of M + Cu. – Mesosoma: Scutum, scutellum and axilla densely and deeply punctate ( Figure 3 ) with honeycomb-like hexagonal prismatic punctures; pronotal lobe rectangular and laterally protruding, anterior side with strong lamella; omaulus angular to irregularly carinate. Scutum with short erect yellow-brown to red-brown pubescence; scutellum with deep median emargination; scutoscutellar suture wide and deep, axillar suture much narrower, yet distinctly visible. Punctation of axilla somewhat finer than that of scutellum. – Legs: Mid tibia almost as broad as the hind tibia ( Table 1 ); mid and hind tibia widening apically; fore tibia smaller (shorter and narrower) and parallel-sided; distal tarsomeres of all legs lighter brown than the remainder of legs; claws bifidı relatively large arolia present. – Metasoma: Terga smooth, shining; uniformly black without brown apical bands. Terga T1 – T5 with broad impunctate margins, slightly broader in the centre than at sides; disc with fine punctation, interspaces 3 – 4 times a puncture width; punctation of marginal area denser, distance between punctures 1 – 2 times puncture width ( Figure 7 ). Apical visible tergum (T6) with dense, coarse punctation and fringe of ochreous bristles at apex. Scopa dull white.

Derivatio nominis

The name is derived from the Latin adjective ‘ tenebrosus ’ (-a, -um) = ‘ dark ’.

Biology

The type specimen has been collected in May. No other information on biology available.

Remarks

According to the labels attached, the type specimen was examined before by T. Griswold, who determined it as Trachusa rufobalteatum (sic), and by D. M. Baker, who determined it, after comparison with the type of T. ovata , as ‘Protanthidium sp. aff. ovatum Cam. ’. The mandibular dentition, the punctation pattern of the terga and the colouration of the wings are features which characterise T. tenebrosa sp. n. very well, especially as the holotype is a fresh specimen with unworn mandibles and intact wing tips.

Distribution

The type locality is Mount Lambak (Malay: Gunung Lambak) ( Figure 9 ), a small mountain in Kluang District, Johor, Malaysia, where the species was collected in 1971. The summit rises 510 m above sea level, and the area is nowadays protected as a Forest Reserve ( Maniam and Singaravelloo 2015). The area has been developed in recent years as a recreational and tourist attraction called ‘ Mount Lambak Recreational Forest ’, and picnic areas, a car parking, a children ’ s playground and other facilities have been established. This transformation together with the fact that much of Malaysia ’ s surface area has been converted to oil palm plantations may be a conservation concern for the newly described species. On the other hand, habitats similar to those at Mount Lambak can still be found in national parks and forest reserves in southern Malaysia and elsewhere ( Maniam and Singaravelloo 2015), and the species may persist there.

The only known occurrence of the closely related T. ovata is Borneo, in Sarawak, Malaysia ( Cameron 1902; Mavromoustakis 1936; Kasparek 2017). It is more than 800 km away and separated by the South China Sea. This is now an important biogeographical barrier, but during glacial maxima, the Sunda Shelf was largely exposed and these areas were connected.

Differential diagnosis (female)

The habitus of T. tenebrosa sp. n. is very similar to T. ovata . The ground colour of the integument is dark reddish brown to black in both species and this distinguishes them from the other species of the subgenus.

T. tenebrosa sp. n. is distinguished from T. ovata by mandibular dentition ( Table 2 ): it has no clearly distinguishable teeth except the large apical tooth (large apical tooth followed by an edentate ridge), whereas T. ovata has five distinct teeth (one large apical and four smaller subacute teeth). Trachusa tenebrosa sp. n. can be further distinguished from T. ovata by the colouration of the forewing: the outer half of the wing is milky white in T. ovata , contrasting with the strongly infuscate inner part, while in T. tenebrosa sp. n. the wing is infuscated light brown with a less strongly infuscated area confined to the apex beyond the wing cells.

The two species can also be distinguished by the punctation of the metasomal terga (best seen on T2) ( Table 2 , see Figure 7 ): The disc is finely punctured in T. tenebrosa sp. n., with the punctures widely separated from each other (mostly 3 – 4 times their diameter), but they are closer together (mostly 1 – 2 times their diameter) in T. ovata . Because of the larger interstices, the disc appears shiny in T. tenebrosa sp. n. and somewhat dull in T. ovata . The marginal area of T2 is dark brown in T. ovata and black in T. tenebrosa sp. n. The impunctate apical margin of T2 is at least twice as wide as in T. ovata .

The upper omaulus has a continuous carina in T. ovata , whereas there are only discontinuous carinate parts in T. tenebrosa sp. n. The frontal part of the mesepisternum is black in T. tenebrosa sp. n. but reddish brown in T. ovata .

Trachusa tenebrosa sp. n. and T. ovata are both characterised by a regular, honeycomb-like punctation of the head. Most other species in the genus (especially those in the longicornis group) having scattered punctation with large, shining interstices and partly confluent punctures.

Figures

Figure 1. Habitus of the holotype (female) of Trachusa tenebrosa sp. n. in lateral view.

Figure 2. Head of the holotype (female) of Trachusa tenebrosa sp. n.

Figure 3. Mesosoma of the holotype (female) of Trachusa tenebrosa sp. n.

Figure 4. Mandibles of the females of Trachusa tenebrosa sp. n. (left) and T. ovata (right). The apical tooth is broader, and the inner teeth merged to a tooth ridge in T. tenebrosa as compared to T. ovata.

Figure 5. Mandibles of the females of Trachusa tenebrosa sp. n. (left) and T. ovata (right).

Figure 6. Wings of Trachusa tenebrosa sp. n. (female holotype, top), T. ovata (female holotype, below). – Photographs by the author and D. Notton, NHMUK.

Figure 7. Punctation of T2 of Trachusa tenebrosa sp. n. (left) and T. ovata (specimen from SEMC; right). Note the finer punctation with wider interstices and the broader impunctate apical margin in T. tenebrosa sp. n.

Figure 8. Abdominal terga of Trachusa tenebrosa sp. n. (left) and T. ovata (right). Note the denser punctation with larges punctures in T. ovata.

Figure 9. Distribution of Trachusa (P.) tenebrosa sp. n. and T. (Paraanthidium) ovata.

Tables

Table 2. Comparison of the main characters distinguishing the two members of the ovata species

	T. tenebrosa sp. n.	T. ovata
Dentition	One large apical tooth followed by an	One large apical tooth and four distinct
	edentate ridge consisting of merged teeth	subacute teeth.
Fore wings	Fore wing light brown infuscated, outer one	Inner half of fore wings strongly infuscated
	third (beyond the wing cells)	brown, outer half milky white brightened.
	inconspicuously brightened.
Punctation and	Entirely black. Smooth and glossy disc with	Black disc with a dark brown marginal zone.
colouration of T2	fine punctation; punctures widely	Disc with coarse, dense punctation,
	separated from each other (3–4 times their	punctures separated by 1–2 times their
	diameter). Relatively wide impunctate	diameter. Narrow impunctate margin,
	margin, slightly attenuated laterally.	punctures reach margin at sides.