A revision of the genus Dehaasia (Lauraceae) in the Indo Burmese region

A taxonomic revision of the genus Dehaasia Blume is presented for the Indo Burmese region. Four species are recognized, keyed out and treated with references, type citations, synonymy, flowering and fruiting periods, local names and use, habitat, distribution and the specimens examined. Dehassia rangamattiensis is synonymized under D. kurzii. The report of D. firma from the Andaman Islands is based on a misidentified specimen of D. kurzii. The names Dictyodaphne candolleana (basionym of D. candolleana ), D. kurzii , D. rangamattiensis and Laurus incrassata (basionym of D. incrassata ) are lecto-typified. In addition, lectotypification of Cryptocarya cuneata (basionym of D. cuneata ), native to Malesia, is appended because the species has often been mistaken for D. candolleana.


Introduction
The genus Dehaasia Blume comprises about 35 accepted species distributed from China, Northeast India and Southeast Asia to New Guinea (1). The generic name is orthographically conserved against Hassia Blume (2). The genus is characterized by the alternate, penninerved leaves, paniculatecymose inflorescences, trimerous bisexual flowers, semipersistent unequal tepals, nine bilocular stamens, the fruits usually subtended by swollen or thickened and sometimes coloured pedicels. It is closely related to Alseodpaphne Nees, differing only in the 2-locular rather than 4-locular anthers (3,4). Hooker (5) revised Dehaasia in erstwhile British India and accepted four species of which three species were shown to be distributed in the Indo-Burmese region. Kostermans (3) presented a synopsis of Dehaasia and accepted 35 species. He (6) eventually described D. assamica from Meghalaya, India. Subsequently Mathew and Lakshminarasimhan (7) reported the occurrence of the Malesian D. fimra Blume from the Andaman Islands. Gangopadhyay (8) described two new species from the area, one from Bangladesh (D. rangamattiensis M.Gangop.) and the other presumably from Arunachal Pradesh, India (D. arunachalensis M.Gangop.). He also reported the occurrence of the Malesian species D. incrassata (Jack) Kosterm. in the Nicobar Islands, India. Pandey and Diwakar (9) enumerated the occurrence of 5 species of Dehaasia in the Andaman and Nicobar Islands while Chakrabartyet al. (10) recorded four species in these Islands. nizes four species in the area. A number of confusions and misidentifications have been clarified here and it is hoped that this presentation will be helpful in the accurate identification of the taxa occurring in the region. Five names are also lectotypified.

Materials and Methods
The present investigation was carried out based on the study of literature and available herbarium specimens housed at CAL, G, K, L, MICH, P, PBL and U. Of these, the specimens at CAL and PBL were studied physically whereas the materials of all other herbaria were studies through online resources. The descriptions were prepared based on dried materials except for the flowers, which were expanded by soaking in water for dissection and then measured under an Olympus SZ-61 stereomicroscope. The systematic treatment contains generic nomenclature, citation of type and description. The key to the species is then presented. Detailed nomenclature, typifications and descriptions are provided for each species. The vernacular names and uses, if any, flowering and fruiting periods and distribution of each taxon treated are indicated. Selected specimens examined during the present revision are also cited. Shrubs or trees; twigs usually greyish, with prominent leaf scars; terminal buds not perulate. Leaves alternate, crowded near apices of branches, often glaucous beneath, entire, penninerved; petioles channelled above. Inflorescences axillary and subterminal, slender, paniculate-cymose, pedunculate, repeatedly branched; ultimately flowers arranged in dichasia; lateral flowers of dichasia opposite; axis pubescent to glabrous. Flowers: trimerous, bisexual, distinctly stalked; tepals 6, unequal, the outer 3 usually smaller than the inner 3, deciduous or persistent; stamens 9, triseriate; anthers 2-locular, first and second whorls introrse, third whorl extrorse and biglandular (on filaments); ovary sessile; style short or long; stigma simple or peltate. Fruits with thin mesocarp, seated unprotected on pedicels; fruiting pedicels usually thickened and coloured. Trees (stature unknown); young shoots brown tomentellous; branchlets blackish, terete, glabrous. Leaves narrowly oblong, elliptic-oblong to oblong-oblanceolate, 9 -25 × 2-6.5 cm, acute to cuneate at base, obtuse and apiculate at apex, chartaceous, glabrous, blackish above when dry, pale brown beneath, not glaucous; midrib impressed above, raised beneath; lateral nerves 8-12 pairs, arcuate, flat and prominent above, raised beneath; tertiary nerves faint above, prominent beneath, scalariform; reticulations of minor nervules faint above, prominent beneath; petioles 1-1.5 cm long, glabrous. Flowers: not seen. Infructescences paniculate, ca 13 cm long. Fruits globose, 1.5-2 cm in diameter; fruiting pedicels slightly thickened, 1-1.3 cm long.

Habitat
Occurring at about 1300 m altitude.

Specimens examined
Known from the type collections only.

Notes
Dehaasia assamica was described by Kostermans (6) based on the single specimen of Thakur Rup Chand 2778 from Garo hills, Near Nokrek which was housed at L. A duplicate of this collection is now found to be housed at MICH. Therefore, the specimen at L bearing annotation by Kostermans is the holotype and its duplicate at MICH is the isotype. The above description is based on the study of the images of the type and protologue. Dehaasia arunachalensis was described based on a specimen devoid of any herbarium label. From the description and the drawing, it is evidently very close to D. assamica, and perhaps conspecific, apparently differing only in the somewhat stiffer texture of the leaves. However, as we could not examine the type, it is indicated here as a synonym with a question mark to draw attention of the future workers because occurrence of the species is quite expected in Arunachal Pradesh and the stiffer texture of the leaves may eventually found to be individual variations of a single species only. Trees, 5-20 m high; young shoots sparsely pubescent to glabrous; branchlets greyish or brownish, terete, glabrous. Leaves cuneate-obovate to orbicular-obovate or occasionally obovate-oblong to oblanceolate or oblongelliptic, 10-34 × 4-13 cm, cuneate to cuneate-attenuate at base, sometimes decurrent into petioles, rounded to obtuse or sometimes apiculate or occasionally acuminate (acumen ca 10 mm long) at apex, chartaceous to thinly coriaceous, glabrous, greenish-brown or blackish or chocolate-brown to dark brown above (often glossy) when dry, pale brown, chocolate-brown and often glaucous or glaucescent beneath; midrib sunken or impressed above, raised beneath; lateral nerves slender, 6-12 pairs, straight or arching uniformly, flat and prominent above, raised beneath; tertiary nerves prominent to obscure above, prominent to faint beneath, scalariform to percurrent; nervules finely reticulate, prominent to obscure above and beneath; petioles 1-4 cm long. Panicles terminal and axillary, 5-16 cm long, glabrous. Flowers: pedicels 2-5 mm long; outer tepals deltoid to suborbicular, 0.5-1 × 0.8-1.8 mm; inner tepals broadly ovate to suborbicular, ca 2.5 × 2.3 mm; stamens ca 2.5 mm long; ovary globose, ca 1.5 mm in diameter; style ca 1 mm long. Fruits globose or sometimes broadly ovoid, 1.5-3 cm long, 1.5-2.5 cm in diameter, smooth; fruiting pedicels 0.3-1.8 cm long, thickened, fleshy.

Habitat
Common on the edges of forests or inland forests up to 200 m altitude.

Distribution
India (Nicobar Islands), Thailand and throughout Malesia.

Notes
Jack (15) described Laurus incrassata based on his collections from Natal, Bencoolen in Sumatra and cited "Machilus medius. Rumph: Amb: 111. p. 70. T. 41". Thus, the Rumphius drawing cited by Jack also belongs to original materials. As most of the Jack's collections were destroyed by fire during transit to Europe (1,16,17), we designate here the Rumphius drawing as lectotype in the absence of herbarium specimens collected by Jack. The neotype of Laurus incrassata designated by Fijridiyanto et al. (14) becomes redundant herewith as per Art. 9.19 (2). Fur-ther, the lectotypification of Hassia microcarpa by Fijridiyanto et al. (14) is also superfluous because of an earlier effective lectotypification (3). However, in case of D. media, Kostermans (3) cited a specimen and drawing as the type which is not an effective lectotypification.

Uses
Timber is used for the construction of houses in Myanmar.

Habitat
Scattered from coastal to inland forests on loamy soil up to 200 m altitude (Andaman Islands); up to 500 m in Myanmar.

Distribution
India (Andaman Islands), Myanmar and Thailand.

Notes
There was no requirement to specify a single herbarium before 1990 as per Art. 9.22 (2), so long as the type element (the single gathering) is indicated (Art. 7.11). Thus, the citation of type by Kostermans (3) conforms to first-step lectotypification (N.J. Turland, pers. comm.). Hence, a secondstep lectotype is designated here following Art. 9.17 (2).
The lectotype bears pencil drawings of flowers by Hooker. The remaining syntypes of D. kurzii from the Andaman Islands, India represent D. candolleana. Thus, D. kurzii, when described, was a mixed assemblage and the present lectotypification narrows it to a single element, enabling unambiguous use of the name. In the case of D. rangamattiensis, Gangopadhyay (8) cited "J.S. Gamble 7969 (CAL)" as the holotype in the protologue. This collection, Gamble 7969, consists of two duplicates at CAL and these two specimens are syntype under Art. 40.2 Ex. 3 (2). Therefore, we designate here one of the sheets (CAL0000033951) as the lectotype. The report of D. firma by Mathew & Lakshminarasimhan (7) is based on a specimen of D. kurzii.

Notes
The protologue of Cryptocarya cuneata cites the locality as "In sylvis Insulae Nusae Kambangae" (18). Kostermans (3) cited the type as "Typus: BLUME, Java, Nusakambangan, fl. (L)." Fijridiyanto et al. (14) cited the type as "Type: Blume s.n. (holo L.0036313; iso L.00336315), [Indonesia] Java, Nusa Kambangan." It may, however, be mentioned that there are two specimens at L from Nusa Kambang, Java, collected by Blume (L0036315, L0926399, images!) which may be regarded as the uncited original material of the name (Art. 9.4) (2). The third specimen (L0036313, image!) although not bearing the specific locality, was identified by Blume in his own handwriting as "Cryptocarya cuneata Bl." Thus this specimen is also the original material of the name. All these specimens bear annotations by Kostermans. As these specimens do not represent a single gathering, the citation by Kostermans (3) cannot be accepted as the first-step lectotypification as per Art. 9.17 and 9.19 (2). Hence, the best flowering specimen out of these three is designated here as lectotype of C. cuneata. .