Alcidodes crassus ( Pascoe, 1882 )

Lyal, C. H. C. & Curran, L. M., 2000, Seed-feeding beetles of the weevil tribe Mecysolobini (Insecta: Coleoptera: Curculionidae) developing in seeds of trees in the Dipterocarpaceae, Journal of Natural History 34 (9), pp. 1743-1847 : 1781-1788

Alcidodes crassus ( Pascoe, 1882)

Alcides crassus Pascoe, 1882: 450 ; Waterhouse, 1885: plate 161, ®gures 8, 8a (no text); Heller, 1917: 212 (keyed), 224 (including his undescribed new species hoplomachus ).

Alcidodes crassus Pascoe ; Kalshoven, 1956: 82; Haaf, 1961e: 484; 1964a: 37; 1964b: 172; Pajni and Dhir, 1987: 34 (listed).

Large insects, length 9±13.4 mm (xÅ5 11.93), PW 5 4.25±6.75 mm (xÅ5 5.72), HW5 5±8.3 mm (xÅ5 7.23) (n 5 10) (®gures 21, 53, 73).

Head. Rostrum not greatly curved, more slender, less punctate and much longer in female (RL 5 5.0± 8.75 mm, xÅ5 7.61 mm; RL/PW 5 1.2±1.3; RB/RD 5 0.5± 0.75; n 5 6) (®gure 184) than in male (RL 5 5.0± 5.1 mm; RL/PW 5 0.87±0.91; RB/RD 5 0.8±1; n 5 4) (®gure 185).

Thorax. Sides of thorax in dorsal view relatively weakly sloping (®gure 31, 53); PL/PW, m, 0.74±0.8 (xÅ5 0.77, n 5 7),, l0.72±0.76 (xÅ5 0.74, n 5 4); prothorax with tooth posterior to coxa. Elytra with interstriae smooth or weakly wrinkled proximally, strial punctures shallow or deep, subequal in width to width of interstriae, humeri with interstria 9 sometimes projecting beyond 8 in dorsal view, although generally concealed by 8 just posterior to humerus; EL/HW, m, 1.16±1.22 (xÅ5 1.19, n 5 7),, l1.12±1.17 (xÅ5 1.15, n 5 4). Elytral pigmentation and scale cover uniform, although scales sometimes sightly denser posteriorly than on rest of elytron. Fore femur with ventral tooth subtriangular, lacking proximal lobe, proximal margin at c.90ss to the long axis of the femur and almost invariably shorter than the length of the tooth, distal margin dentate or serrate (®gures 129, 147, 148); all tibiae with small ventral tooth. Metasternum strongly raised before hind coxae, strongly diverging from elytral margin (®gure 73, cf. ®gure 12).

Abdomen. Ventrite 5 with two caudal setal tufts generally on weak prominences in both male and female, those of male larger than those of female; male ventrite 5 sometimes weakly depressed medially (®gure 92), female ventrite 5 depressed laterally posteriorly (®gure 93).

Male terminalia. Tergite 7 as in ®gure 221; short row of plectral tubercles on each side. Segment 8 as ®gure 222. Genitalia as in ®gures 223±228. Tegmen with parameres fused at base (®gure 224). Aedeagus with apex rounded, sometimes weakly acuminate, sides weakly converging and roughly parallel, sclerotization extending onto dorsal surface only slightly (®gure 226) or more extensively, AL:AW5 3.95±4.32 (xÅ5 4.09, n 5 3), distance from ostium to apex subequal to width of ostium (Andamans specimen) or less than width of ostium (Malaysian and Javanese specimens) (®gures 226, 227). The ductus ejaculatorius is notably broad in Malaysian and Javanese specimens (see comments below).

Female terminalia. (®gures 229±231) Tergite 7 with scattered plectral tubercles on each side of midline (®gure 221). Tergite 8 with rounded posterior margin, weakly sclerotized anteriorly (®gure 230). Female genitalia as in ®gures 232, 233; spermathecal duct arising at junction of bursa and oviduct; spermatheca with simple tubular gland lobe; hemisternites with very large ¯attened styli.

Distinguishing features. This is one of the largest species in the group, and is very similar to A. hoplomachus . Together with its size, the greatly elongate rostrum of the female makes members of these two species fairly easy to pick out. A. crassus has a much narrower distribution than hoplomachus , being restricted to the Andaman Islands, Peninsular Malaysia and perhaps Java (see below), while hoplo - machus is found between India, the Philippines and Borneo. The characters distinguishing crassus from hoplomachus are given under that species.

Comments. Prior to this study the range of A. crassus was believed to extend from India through mainland Asia to Borneo and the Philippines. However, examination of the male genitalia and external morphological features has led to a restriction in the species concept and the published range of the species. Most specimens, including the type series, have been collected from the Andaman Islands, although no host is known at present. Other specimens have been collected from Peninsular Malaysia and Java. These are so similar to the Andamans specimens that they are considered here to be the same species, although there are indications of divergence. The major diOEerences are in the male genitalia, which in the Javanese specimens and one of the Malaysian specimens have the sides extending far more onto the dorsal surface of the`body’ of the aedeagus than in the Andamans males; the aedeagus is also somewhat broader. A second Malaysian specimen has the aedeagal sides as in the Andamans specimens, but again the aedeagus is relatively broader. The endophallus sculpture is slightly more marked in the Malaysian and Javanese specimens than in the Andamans specimens, and the ductus ejaculatorius somewhat broader. Unfortunately, having only two Malaysian males and two Javanese males available for examination limits the strength of the conclusions that can be drawn. The females do not appear to exhibit any characters that permit diOEerentiation between the geographical areas and, indeed, the two females available from Java diOEer externally in that one has a relatively narrow fore femoral tooth, similar to that of A. toyi . The safest conclusion to be drawn at this stage is that the species extends from the Andaman Islands through Peninsular Malaysia to Java (and thus is likely to be found on Sumatra and its oOEshore islands), but gene ¯ow across that range is limited, perhaps leading to isolation of populations in diOEerent areas. This being the case, host preferences cannot be assumed to be the same over the whole region.

Because of the much broader species concept employed in the past, the many host records for À. crassus ’ must be treated with extreme caution, or discarded. These records include: (1) Dipterocarpus alatus Roxb. (Sen-sarma and Thakur, 1986Ðpers comm. from J. Intachat); (2) D. baudii Korth ( Daljeet-Singh, 1974) , which does occur within the distribution of A. crassus ; (3) D. dyeri Pierre (Daljeet- Singh, 1974), which does occur within the distribution of A. crassus ; (4) D. grandi - X orus Blanco ( Beeson, 1941, 1961; Hutacharern and Tubtim, 1995), which on the basis of known associations could refer to A. hoplomachus , although A. crassus does occur in the area covered by the publications; (5) D. hasseltii Blume ( Kalshoven, 1956) , which on the basis of known associations could refer to either A. hoplomachus or A. curranae , although A. crassus does occur in the area covered by the publication; (6) D. macrocarpus Vasque. ( Mathur and Balwant, 1959) ; (7) D. oblongifolius Bl. ( Daljeet-Singh, 1974) ; (8) D. tuberculatus ( Mathur and Balwant, 1959) , which is known as a host of A. dipterocarpi , but which occurs in areas where A. crassus might also occur; (9) D. turbinatus Gaertner ( Beeson, 1941, 1961; Mathur and Balwant, 1959), the distribution of which encompasses regions where A. crassus has been recorded; (10) Dryobalanop s aromatica Gaertner ( Daljeet-Singh, 1974; Momose et al., 1994), which on the basis of voucher specimens from the latter study are identi®ed here as Alcidodes toyi ; (11) Dryobalanop s oblongifolia Dyer ( Daljeet-Singh, 1974) which, while specimens from this host have not been seen, probably refers to A. toyi since all other Alcidodes collected from Dryobalanops species have proven to be that species; (12) Hopea acuminata Merrill ( Beeson, 1941, 1961; Mathur and Balwant, 1960a), a host from which no specimens of A. crassus have been seen, the records probably referring to A. walliorum , A. fugitus or A. confusus ; (13) Shorea guiso Blanco (Bl) ( De Mesa, 1935), a Philippine record from outside the range of A. crassus , as well as from an inappropriate host; (14) Shorea spp. ( Beeson, 1941, 1961; Mathur and Balwant, 1961), records almost certainly referring to other species of Alcidodes , since no specimens of A. crassus from any Shorea species have been seen in this study.

Gardner (1934) described the larva of what he believed to be Àlcides crassus ’, and used this in his 1938 key to larvae. His specimens were reared by C. F. C. Beeson from seeds of Dipterocarpus pilosus (now D. gracilis ) in Lakhimpur, Assam, a locality in which Alcidodes crassus is unlikely to be found. There are, however, specimens of A. hoplomachus in the collections of the BMNH collected by Beeson from this locality and host, suggesting Gardner’s larval descriptions are of this species. Dipterocarpus pilosus Roxb. has been recorded as a host of A. crassus by Beeson (1941, 1961) and Mathur and Balwant (1959), the last-cited probably referring to the record published by Beeson.

There are several manuscript names for this species, apparently never published. One specimen in the BMNH is labelled Àlcides trigonus Pascoe’, another is labelled Àlcides triangulum n. sp. ’, and one in the MNHN is labelled `triangularis Db; triangulum olim.’. The BMNH specimen labelled `triangulum ’ is of the same series as one of the MNHN specimens.

Specimens examined

LECTOTYPE m, Andaman Islands , here designated, with labels:`Andamans’ (Pascoe’s handwriting, green oval) and` Alcides / crassus / Type Pasc.’ (Pascoe’s handwriting) and`LECTO- / TYPE’ (printed disc) and`SYN- / TYPE’ (printed disc) and` Type / H. T.’ (printed disc) and`Pascoe Coll. / 93±60’ (printed) and ` LECTOTYPE / Alcidodes crassus / Pascoe m / Lyal det. 1994’ (printed) and`4’ typed. ( BMNH) .

PARALECTOTYPES: Andaman Islands , 1, l 2mm, same data as lectotype. ( BMNH) .

Other material. Andaman Islands : 1m (Fry Collection); 1, l 1m (Roepstor V; Fry Coll.); 1m (Atkinson Coll); 1m (Williams; Fry Collection; specimen noted in Fry’s register as type of Alcides trigonus Pascoe , but name apparently never published) (all BMNH) ; 1 l(labelled as Alcides triangulum n. sp., but name apparently never published) (BMNH); 1 l(Marshall) (USNM); 1, l 2mm, (NMHN).

Malaysia: Peninsular Malaysia: 1, l Selangor, Bukit Kutu , 3,600¾, 13 September 1929 (H. M. Pendlebury); 2 ll, 2mm, Negri Sembilan, Ulu Serting (Toy),`169’ ex Dipterocarpus cornutus (all BMNH) .

Indonesia: Java: 2 ll, 2mm, Peloalongan, in fruits of Dipterocarpus trinervis (now D. retusus ) ( BMNH).

Range. Andaman Islands, Peninsular Malaysia, Java.

Hosts. Dipterocarpus cornutus Dyer , D. retusus Bl.