8. HERPETOLOGY OF RENNELL ISLAND

' BY

HELGE VOLS0E ZOOLOGICAL MUSEUM, COPENHAGEN

INTRODUCTION

The present paper is based on two collections of reptiles from Rennell Island in the Solomon Group. The first of these collections, comprising 51 specimens, was made by a Danish expedition (Dan. Exp.) under the leadership of Mr. T. W o lff, M. Sc. This expedition which was sent out by the Galathea Expedition Round the World 1950­ 1952 stayed on Rennell Island from 12 October to 14 November 1951 (W o lff 1955b). The second collection, comprising 18 specimens, was made by a British expedition (Brit. E-Np.) sent out by the British Museum (Natural History) and consisting of Mr. J. D. Bradley and Mrs. Diana Bradley; they stayed on Rennell Island from 15 October to 27 November 1953, and on their way back they paid a two day visit to , where, however, no reptiles were collected (B radley 1955). The two collections are kept in the Zoological Museum of Copenhagen and the British Museum (Natural History) respectively. - To these institutions and to the above collectors I extend my best thanks for handing over the material to me. I am further indebted to Squadron Leader M arshall Laird, University of Ma­ laya, and to Dr. Walter Brown, Standford University, California, for permission to publish records of 4 species collected on Bellona Island 15-16 August 1953 by Mr. & Mrs. Marshall Laird in the course of a malariological project initiated by the Royal Air Force. The specimens were identified by Dr. B rown.

SAURIA gekkonidae Gehyra oceanica (Lesson)

This species has not previously been recorded from Rennell Island, but the Templeton

Crocker Expedition collected 3 specimens on Bellona Island (S levin 1934). - While none of the 16 specimens of geckos collected by the Danish expedition belongs to this species, one of the three specimens collected by Mr. B radley is this species. It is labelled “Rennell Island” without exact locality. This house-gecko is wide-spread in the Pacific islands and apparently easily trans­ ported from one island to another. It is rather surprising that it is so rare on Rennell Island, for it has been recorded from all the islands around Rennell (New Hebrides, Santa Cruz, Solomons) and also from New Guinea and Queensland. Gekko vittatus Houttuyn

Previous records: The Templeton Crocker Expedition (S le v in 1934) collected this species on Rennell as well as on Bellona Island. M ate ria l: The Danish expedition collected 13 specimens from the following localities on Rennell Isl.: St. L. 356, Lavanggu, 6 spec.; St. L. 364, Te-Avamanggu, open, cultivated area, mainly grassland, 2 spec.; St. L. 379, Niupani, Lake Te- Nggano, sun-exposed grassplain near lake, 1 spec.; St. L. 380, Niupani, Lake Te- Nggano, coconut-grove with scattered bush-growth, 2 spec.; St., L. 384, Niupani, Lake Te-Nggano, 2 spec. - The British expedition collected two specimens, one labelled “Hutuna” (at the lake), the other “Rennell Island” . This tree-gecko is distributed from the Moluccas through New Guinea and the to the and the Banks Group, the latter marking its southeastern limit of distribution (Burt & Burt 1932). Judging from the numerous specimens collected it seems to be the most common gecko on Rennell Isl. The specimens vary in head-body length between 45 mm and 123 mm. A vertebral stripe is absent in most specimens and only faintly indicated posteriorly in some specimens. - M arshall Laird found the species in the Ngongona area on Bellona Island. Three sets of gecko-eggs, two collected by the Danish and one by the British expedition, all on Rennell Island, belong to this species, although they are somewhat larger than the measurements given by d e R o o ij (1915): 16 x 18 mm, 17 x 17 mm, and 14 < 18 mm resp. Each egg has two flattened surfaces, one towards the substra­ tum to which they are attached, and one towards the other egg in the pair. One egg was opened and the large embryo could be identified as belonging to the present species.

Gymnodactylus pelagicus (Girard)

Not previously recorded from Rennell or Bellona Islands. M a te r ia l: Two specimens collected on Rennell by the Dan. Exp.: St. L. 352, co­ conut grove, under stones and plant debris; St. L. 356, Lavanggu. This species is known from New Guinea and Queensland and has been recorded from all the islands around Rennell Island and from many other islands in the Paci­ fic, so its occurrence on Rennell is not surprising.

Lepidodactylos lugubris (Dumeril & Bibron)

Not previously recorded from Rennell or Bellona Islands. M ate ria l: One specimen (38 mm head-body length) collected by the Dan. Exp.: St. L. 356, Lavanggu, Rennell Isl. S le v in (1934) recorded L. guppyi Boulenger from Rennell Isl. The present specimen has, however, a very distinctly flattened tail and must therefore be referred to lugubris. It seems curious that the only two specimens of Lepidoclactylus collected on Rennell should belong to two difl'erent species. However, the distribution of the two species does not speak against the occurrence of both species on Rennell Island. L. lugubris is the most widely distributed of the two species, ranging from Ceylon through the East indies to many islands in the Pacific, while L. guppyi is restricted to New Guinea, the Solomons’and the Santa Cruz group. In the Solomon Islands L. lugubris is apparently the rarer of the two species, the first exact record from this group being that of S c h m id t (1932), although d e R ooij (1915) included the Solomon Islands in the range of the species. Being a house-gecko it is probably transported by man in boats, which may account for its scattered and rare occurrence in the East Indies.

Lepidodactylus guppyi Boulenger

One specimen collected on Rennell Island by the Templeton Crocker Expedition 1933 (Slevin 1934). - For discussion see under the foregoing species.

SCINCIDAE [CrTptoMepharns bontonii poecilopleunis (Wiegmann)

Five specimens of this species were collected on Rennell Island by the Templeton Crocker Expedition in 1933 (S le v in 1934). It is not represented in either the collec­ tions of the Whitney Expedition (Burt & Burt 1932) or in the collections of the Danish and the British expeditions treated here. - The occurrence of this form on Rennell Island is remarkable, because it does not occur in New Guinea, the Solomon Islands, the Santa Cruz Islands and the Banks Islands.]

Emoia cyanura (Lesson)

P rev io u s reco rd s: The Templeton Crocker Expedition collected 7 specimens on Rennell Island and 14 specimens on Bellona Island (S le v in 1934).

M aterial:

Scales from Lamellae Head-body Longitud. occiput to under fourth • length mm scale rows base of tail toe

Dan. Exp. St. L. 352 43 30 54 67 - - - L. 363 40 31 51 66 - - - L. 363^ 35 30 55 69 - - - L. 364 43 30 56 69 Brit. Exp. no. 1 35 30 52 64 - - - 20 42 28 59 66 - - - 104 42 28 57 65

All'the specimens listed above are from Rennell Island. They were collected both in cultivated areas and in the rain forest. All the specimens, some of which are fully 1. From the stomach of a nestling of the kingfisher Halcyon chloris amoena Mayr. t grown, have the typical colouration: back brown with three distinct golden longi­ tudinal stripes, the vertebral one being the broadest. The tail is bluish with two rows< of brown dots in continuation of the black dorsal stripes. * The data presented in the table above show that the range of variation in meristic characters falls well within the general range of variation of the species as seen from the very large collection of the Whitney Expedition (Burt & Burt 1932). The species is widely distributed in the East Indies, the Melanesian and Polynesian Islands. It is apparently one of the most easily transported lizards.

Emoia nigra (Hombron & Guichenot)

Previous records: Collected by the Whitney Expedition on Rennell (2 specimens) (Burt & Burt 1932) and by the Templeton Crocker Expedition both on Rennell (14 specimens) and Bellona (16 specimens) (S le v in 1934).

M a te ria l:

Scales from Lamellae Head-body Longitud. occiput to undar fourth length mm scale rows base of tail toe

Dan. Exp. St. L. 351 90 36 71 31

- - - L. 353 102 36 62 32

-- - L, 353 94 33 66 32

-- - L. 356 100 37 64 31

-- - L. 357 83 38 65 33

-- - L. 363 86 38 66 31

- - - L. 363 78 38 62 30

- - - L. 372 105 35 64 33

-- - L. 376 58 38 70 31 -- - L. 388 108 40 64 32

- - - L. 388 118 36 63 31

- - - L. 388 83 34 67 30 -- - L. 388 70 34 67 31 -- - L. 388 51 34 64 30 Brit. Exp. no. 8 65 36 65 32 - - - 16 80 35 64 33

- - - 38 93 37 65 33

-- - 41 95 37 65 30

All the specimens listed above were collected on Rennell. The stations are partly in cultivated districts, partly in the rain forest (see W o lf f 1955 b). The colouraliofi is about the samein all the specimens; the back is darker or lighter brown with dark and light spots. A very prominent character in all the specimens is the yellowish edges of I the eyelids, a character which I have not seen mentioned in the literature and by *vhich this species is easily distinguished from all other skinks in these islands. B urt *& Burt (1932) have shown that the range of variation of the meristic characters is about the same throughout the range of the species. The material listed above falls well within this range of variation. This species has a less extensive distribution than the preceding one; it ranges from the Solomon Islands through Banks Islands, Santa Cruz Islands, the New Hebrides to .

[Emoia atrocostata (Lesson)

S le v in (1934) records this species from Bellona Island, where the Templeton Crocker Expedition collected one specimen. This record together with S c h m id t’s record of a single specimen collected on Ysabel Island seem to be the only records of the species from the Solomon group.]

Riopa rufescens (Shaw)

No previous records from Rennell or Bellona Islands. M a te ria l: Two specimens collected by the Dan. Exp. on Rennell Island, St. L. 363 and L. 364, 18.10. l'951. The data of the specimens are as follows

no. 1 no. 2 Length of head and body 91 mm 93 mm - - tail - 142 - Longitudinal scale rows on midbody 30 28 Scales from occiput to base of tail 74 66 Lamellae under fourth toe 17 16

Both specimens are uniformly dark brown above and yellowish below, without any trace of transverse bars. The occurrence of this species on Rennell Island is rather unexpected, since it is not known east of New Guinea (and the D ’Entrecasteaux group). The closely allied species R. albofasciolaia (Gunther) was more likely to occur on Rennell, because it is known from the Solomons and the Santa Cruz group. However, the low number of midbody scale rows in the two above specimens makes it impossible to refer them to that species.

VARANIDAb Varanus indicus indicus (Daudin)

P rev io u s reco rd s; The Whitney Expedition collected two specimens on Rennell (Burt & Burt 1932) and the Templeton Crocker Expedition another two specimens on Rennell (S le v in 1934). M arshall Laird (see p. 121) collected it on Bellona Island (identified by W alter Brown and kept at Stanford University). M ate ria l: Lei of head and body ' tail no. 1 Dan. Exp. St. L. 353 285 mm 450 mm - 2 - - - L. 356 270 - 450 - - 3 - - - L. 372 260 - 440 - - 4 Brit. Exp. no. 383 290 - 445 - - 5 - - - 112 100 - 148 -

Specimen no. 5 has an open umbilicus, so it is apparently newly hatched. The species Varanus indicus is widely distributed in the eastern part of the East- Indian archipelago fromTalaud and Timor to New Guinea and the Solomon Islands; it is furthermore found in Queensland. While it has spread from the Papuan region towards northeast throughout Micronesia (Caroline, Marianne and Marshall Islands), it has not spread eastwards and southeastwards from the Solomon Group, it has not been recorded from the Sta. Cruz Islands, which are only 400 km east of the Solomons. The nominate subspecies occupies the whole distributional area except two small islands (one of which is George Island in the Solomons) where endemic subspecies have evolved. The specimens from Rennell Island do not show any deviations from the typical subspecies either in colouration or in scutellation, although Rennell Island is much more isolated from the rest of the archipelago than is George Island.

BOIDAE Eoygrus bibroni australis (Montrouzier)

Not previously recorded from Rennell Island, but M arshall Laird (see p. 121) collected two specimens on Bellona Island. M a te ria l: One specimen (?) collected by the Dan. Exp. on Rennell Island, St. L. 363 (rainforest, 3-6 miles from the coast, WNW of Lavanggu, 16.10.1951). - Ventrals: 256; subcaudafs: > 40 (tip of tail missing); midbody scale rows: 38. Head-body length: 1870 mm, total length (tip of tail missing): 2060 mm. - This is a remarkably large specimen, being nearly twice as long as the largest hitherto recorded specimen (Boulenger (1893): total length 1130 mm). Since the ovaries are degenerate it is prob­ ably a very old female. S t u l l (1935) followed Roux (1913) in considering the two forms bibroni and au­ stralis subspecies of the same species. I have adopted this procedure although, as pointed out by Burt & Burt (1932), the two forms overlap to some extent; for instance both forms occur in the Loyalty Islands. However, the two forms are obviously closely related and easily transported from one island to another; it is still to be proved that they keep separate in the places where they meet. The species bibroni (s. 1.) is widely distributed in the southwestern Pacific, from the Bismarck Archipelago in the west to the in the east; australis mainly occupies the western part of this area, bibroni the eastern part. E. b. australis occurs on all the islands around Rennell Island (the Solomons, Sta. Cruz, New Hebrides) except the Banks Islands from which bibroni is recorded. Enygrus bibroni has apparently great climbing abilities, for the two specimens cpilected by L a i r d (see above) were shot down from a branch 10 m above the ground. This ability may be one of the reasons why they are so easily transported from one island to another. Since the generic name of Enygrus has been in common use for more than fifty years I propose not to follow Forcart(1951) in that the name should “correctly” be .

Enygrus carinatus (Schneider)

Not previously known from Rennell Island, but recorded by Slevin (1934) from Bellona Island (1 specimen). M a te ria l: The Dan. Exp. and the Brit. Exp. each collected 4 specimens, all on Rennell Island. The data of the specimens are as follows:

Scale rows Ventrals Subcaudals Total length

Dan. Exp. St. L. 356 37 189 36 665 mm - - - L. 363 37 192 35 480 - - - L. 372 ■ 39 194 35 507 - - - - L. 372 35 192 35 618 - Brit. Exp. no. 107 35 192 37 730 - - - - 108 37 192 39 320 - - - - 109 36 188 39 460 - - - - 110 36 190 35 500 -

The colouration of all the specimens agree w ith colour variety no. 2 of de R ooij (1917), except that the markings are very faint in no. 108 and have almost disappeared in no. 109 so that this animal appears uniformly redbrown, except on the tail which is normally coloured. - Specimen no. 108 is apparently newly born, for it has a distinct umbilicus. The species is distributed from New Guinea through the Solomon Islands to the Santa Cruz Group. [In the list of Rennellese names of animals (Wolff 1955 c) appears a snake called by the natives te gonitatanga. No specimens of this snake were collected, but Mr. Bradley who recorded the name called it a yellow tree-snake, and he has on my request given the following information (in litt.). “I am afraid I can give you very little information regarding the “yellow tree snake". A specimen was brought to me while at Lake Tenggano but I was unable to preserve it but merely record the name tegonitataga - and that it lived in trees. It was not very big, less than half a metre long, and so far I recall was a mottled yellow and black.” I find it impossible to identify the species on the basis of this description, but merely include it here for the benefit of future collectors.] HYDROPHIINAE Laticauda colubrina (Schneider) r Not previously recorded from Renneli and Bellona Islands. M a te ria l: Two specimens (nos. 1 & 2) were collected by the Dan. Exp. outside the coral reef in Kanggava Bay on 24.10.1951. The Brit. Exp. collected one specimen (no. 3) from Lake Te-Nggano in Nov. 1953. The data of the specimens are as follows:

Scale rows Ventrals Subcaudals Total length Tail length no. I o 23 228 37 790 91 - 2 23 220 41 752 95 - 3 $ 25 226 34 490 47

Since this species of sea-snake is widely distributed in the Indo-Australian Archipelago and in the southern Pacific its occurrence on Renneli Island is not unexpected. Rather remarkable is, however, the occurrence of one of the specimens in a lake. To make sure that it was really found in the lake I asked the collector, Mr. B r a d le y , whether he could confirm this. He answered (in litt.): “It was brought to us by natives while we were camped by the lake, and I was told that it came from the lake. I did not collect reptiles from the coast, and as it was several hours walk, to the sea from where we were at the lakeside I do not think they would have carried it up without making the fact known.” The natives informed Mr. W o l f f that there are two species of sea-snakes in the lake. If the present species is really an inhabitant of the lake, there are, however, three species living in the lake (see below), it is possible that the natives do not distinguish between the two other forms which are both melanistic, while the present specimen is of the usual banded type. For the banded type they have even a special name for youilg specimens ( W o lf f 1955c). The species of the genus Lalicauda are not so completely aquatic as other sea- snakes, and they may sometimes be found on land, although, according to Smith (1926) never far from the sea-shore. Lake Te-Nggano is a rather big lake (about 27 by 8 km) which occupies the eastern end of the central depression of Renneli Island ( W o lf f 1955 a); it represents the rest of the lagoon of this former atoll. It is separated from the sea by a narrow (1-3 km broad) “rim”, but since the rim is about 100 m high, steep on the outside and covered with rainforest it seems extremely doubtful that sea-snakes should NORMALLY cross this barrier. However, the fact that the specimen from the lake is completely identical with the specimens caught in the sea, tend to show that it is a recent invader or that invasions occur sufficiently often to impede segregation. Once in the lake the sea-snakes are probably able to live there and to propagate as wit­ nessed by the two forms which have become endemic to the lake. . Fig. 1. Latieayda latieaudata woffi new subspecies. - Head of type specimen.

Laticauda latieaudata wolffi new subspecies

Typp; Zoological Museum of Copenhagen, No. R. 668, adult female, collected by T. W olff at Niupani in shallow water (5-25 cm.) near the shore of Lake Te- Nggano. Rennell Island, Solomon Islands, 22. 10. 1951. P a ra ty p e s: Zoological Museum of Copenhagen, Nos. R. 666 (adult female) and R. 667 (adult male), collected with the type; British Museum (Nat. Hist.), collector’s no. 32, collected by J. D. Bradley at Lake Te-Nggano, Nov. 1953. D iag n o sis: Differing from the nominate form in its stouter build, the lower number of ventrals (192-207 against 225-243) and subcaudals (28-29 in females against 30-35, 35 in the male against 38-47), and in the dark melanistic colouration. D e sc rip tio n o f type: Body elongate, thicker and slightly compressed pos­ teriorly (L. I. latieaudata is of nearly uniform diameter throughout). In the scutellation of the head (fig. 1) it agrees almost perfectly with the nominate form: The rostral is higher than broad; there is no azygous shield separating the internasals or prefron- tals; frontal longer than its distance from the end of the snout; one pre- and two postoculars; seven supralabials, the third not touching the eye, the fourth broadly in contact with the eye; temporals 1 + 2; five infralabials in contact with the genials, both pairs of which are well developed (the second longest) and broadly in contact with each other; a series of four small elongated scales at the oral margin after the second infralabial. 19 scale rows throughout; ventrals 193; anal divided; subcaudals 29. C o lo u r: With 29 black or brown-black bands, alternating with interstices, which are dark slate-grey dorsally (almost merging with the black bands), a mottled yellow ventrally. The black bands are broadest ventrally where they cover 6 ventrals and are separated by 2 light ventrals. Head entirely black above, dark brown below without any light marks. M easu rem en ts; Total length 745 mm, tail 76 mm. V a ria tio n : The data of the three paratypes are given below:

Total length, Scale rows Ventrals Subcaudals No. of bands mm

C. M. R. 666 9 19 207 29 31 ab. 750 77 mm C. M. R. 667 d' 19 192 35 31 672 75 - B.M. 9 19 201 28 35 705 60 -

In scutellation of the head the paratypes agree almost perfectly with the type, except that in two specimens the third supralabial is just in contact with the eye. In colouration the paratypes are as the type except that the black bands are equally broad dorsally and ventrally. R em arks: At first I believed that the above specimens belonged to the species Laticauda crockeri described by Slevin (1934) on the basis of a single male from Lake Te-Nggano (= Lake Tungavo Slevin). From the description given of this species the present specimens appear to deviate only in two points: crockeri has 21 scale rows and it is uniformly dark-brown, without bands. While the colour is of little im­ portance, the number of scale rows together with the absence of an azygous frontal shield is clearly a specific character, since the only hitherto known species L,. laiicau- data with the latter character has invariably only 19 scale rows (Smith 1926). D r. Slevin on my request kindly checked his count of his specimen and found that 21 rows is the correct count. Later on Mr. A lan E. L eviton of Stanford University, California, has examined the type and has found that while at midbody the type of crockeri has 21 rows, a short distance posteriorly the scale rows change to 19. Mr. L eviton has also kindly compared one of my specimens with the type of crockeri and has informed me (in litt.) that “it most certainly is not crockeri”. We are therefore faced with the strange situation that this freshwater lake is inhabited by no less than three different species of sea-snakes all belonging to the same genus, Laticauda, namely:

1. L. colubrina. The lake population is undifferentiated from the typical form, which occurs also along the shores of the island (see p. 128). . 2. L. laticaudata woljfi. Subspecifically distinct from the nominate form, which has not been taken from the shores of Rennell Island, but which is known from the coasts of New Guinea, the New Hebrides, and the Fiji Islands, etc. 3. L. crockeri. An endemic species with unknown relationships to other species of Laticauda.

Although the species of Laticauda have sometimes been found on land, there are, as far as I know, no records of their occurrence in freshwater lakes, aside from the present records. The only other sea-snake living in a freshwater lake is Hydrophis semperi Garman from Lake Taal, Luzon in the Philippines. It is interesting that this species also shows a tendency towards melanism. That freshwater as such is not injurious to sea-snakes is shown by the fact that many species frequent estuaries and deltas where the water, at least intermittently, is fresh or brackish. Lake Te-Nggano is a remnant of the lagoon of this former atoll. Although the isurface of the lake is a little above sea level (L aird 1956), the water is slightly brackish with a tothl salinity of about 5%o (W olff 1955 a). The lake has no open outlet to the sea. There are plenty of fish in the lake, among others a freshwater eel (Anguilla pacifica) which probably constitutes the main diet of the sea-snakes.

Laticauda crocked Slevin

The type specimen was collected by Mr. T empleton C rocker in 1933 and is the only specimen collected hitherto. The species was described by Slevin in 1934. His description is as follows: “D iag n o sis. - Body compressed, markedly so posteriorly; head scarcely distinct from neck; snout elongate, rounded at tip; nasal large, occupying most of the pos­ terior part of the nasal plate; no azygous prefrontal present; tip of third labial touch­ ing the eye, the fourth broadly in contact; rostral as high as broad; genials equal in length, the posterior ones not broadly in contact; gastrosteges two and one-half times as broad as long, with lateral keel anteriorly. Scales smooth, in 21 rows; gastrosteges 199; urosteges 39; anal divided; upper labials 1-7; lower labials 8-8; preoculars 2-2; sex o. Color uniform dark-brown, with yellowish anal plate. Total length 479 mm; tail 64 mm.” None of the five specimens of sea-snakes collected in the same lake by the Danish and the British expeditions (1951 & 1953) belongs to this species (see further discus­ sion above, p. 128 and 130).

Pelamis platurus (L.)

Not previously recorded from Rennell or Bellona Islands. Material: One specimen collected by the Dan. Exp. 24/10 1951 at St. M. 516 c, Kanggava Bay, Rennell Island, about 2 km from land. The specimen has a total length of 255 mm, tail length 30 mm. It is black above, yellow below, tail light yellow with irregular black spots (colour var. 1 of Smith 1926). This the m^st widely distributed of all sea-snakes was bound to turn up sooner or later at Rennell Island, since it has previously been recorded from the Solomon Group.

Typhlops olivaceus redunciis Barbour

Not previously recorded from Rennell and Bellona Islands. , Material: One specimen collected by the Dan. Exp. at St. L. 356 (Lavanggu, Rennell Island) on 25/10 1951. The specimen measures 390 mm and has 20 midbody scale rows. A number of new species of blind-snakes endemic to the Solomon Islands, have been described in recent years (T. solomonis Parker 1939; hecki Tanner 1948; hergi Peters 1948; adamsi Tanner 1951). Thereby the number of species recorded from the Solomon Islands is doubled since K ingh orn’s monograph in 1928. In view of the isolated position of Rennell Island in the archipelago it might have been expected that the above specimen represented another new species. This is however not the case; the specimen agrees perfectly with the descriptions of {he widely distributed, species T. olivaceus (from Borneo and the Philippines through the SolOmons to Australia). The subspecies reduncus, the status of which is doubtful, is confined to the Solomon Islands.

GENERAL REMARKS

No amphibians have been recorded from Rennell and Bellona Islands. In this respect these islands form a sharp contrast to the rest of the Solomon archipelago which is inhabited by a fairly rich and peculiar anuran fauna. The absence of anurans on Rennell and Bellona is probably explained by the fact that both these islands are raised coral atolls. The absence of surface water, except for the big lake on Rennell, which has slightly brackish water, has made a later invasion of amphibians impossible. Before the Danish and the British expeditions to Rennell Island 7 species of rep­ tiles were known from that island. The present report adds 10 species to the Rennell list. We have therefore now probably a fairly complete picture of the reptile fauna of Rennell Island. Apart from the sea-snakes of Lake Te-Nggano the reptiles of Rennell Island are of little interest from a zoogeographica) viewpoint. Most of the species are wide­ spread in the Melanesian and Polynesian islands, and they do not show any sign of a beginning endemism. The only exception seems to be Riopa rufescens (p. 125) which has not been recorded east of New Guinea. Whether this species has come to Rennell Island directly from New Guinea (or via the Louisiade Archipelago) or whether it has been overlooked in the Solomons is impossible to decide. It is easy to suggest that the absence of endemisms in the land reptiles of Rennell Island is due to the supposed late emergence of the island (W olff 1955 a). However, the comparatively high degree of endemicity in other animal groups (e.g. in birds, see M ayr 1931) shows that this explanation is not valid. Also the fact that the two species of sea-snakes which became cut off from the sea when the former lagoon was transformed into a lake have had time enough to segregate into an endemic species and subspecies respectively, shows that there has been sufficient time for the evolution of endemism. A lack of endemicity in the reptiles of the oceanic islands of the Pacific seems to be the general rule, even in islands where other animal groups show a high degree of endemicity. The reptile fauna of the contains no forms peculiar to these islands (O liver & Shaw 1953) in contrast to the very peculiar forms of other animals found here. O liver & Shaw explain the absence of endemicity in the reptiles by assuming that they are late immigrants to the islands. All the amphibians and four species of reptiles were probably introduced by man within the last half century. The remaining 7 species of lizards (4 geckos and 3 skinks) are supposed to have been introduced unintentionally by early Polynesian man, probably as late as the twelfth century. M ertens (1934) arrived at a similar conclusion regarding the colonization of the oceanic islands of the Pacific by reptiles. This conclusion is supported by the fact that the fauna of land-reptiles in the coral islands of the Pacific consists of a few widespread undifferentiated species belonging to the families Gekkonidae and Scinci- dae. These species which all have a Papuan origin are specially adapted to trans­ portation in native canoes. The list of land reptiles of Rennell Island is somewhat richer in species than the average coral island of the South Sgas, since, in addition to the widespread “Polyne­ sian” species it contains a few species with a more restricted distribution (Varanus indicus, Riopa rufescens, Enygrus australis & carinalus). This is easily explained by the proximity of Rennell Island to the continental Solomon Islands. This proximity to a continental land mass makes it, however, also difficult to imagine that Rennell Island should have been uninhabited by land reptiles until the arrival of man. I am therefore more inclined to explain the absence of differentiation in the land reptiles in Rennell Island as the result of a continuous addition to the local populations of drift migrants which are carried to Rennell Island on rafts etc., so that the local popula­ tions have never become effectively isolated. The origin of the endemic sea-snakes of Rennell Island has been discussed under these species (see pp. 129 & 130).

LITERATURE

Boulenger, G. a . 1893; Catalogue of the snakes in the British Museum. 2. edit. 1 : 1-448. Bradluy, J. D. 1955: 3. .Account and list of stations of the British Museum (Natural History) Expedition, 1953. - The Natural History of Rennell Island, British Solomon Islands 1 : 43-57. Bu rt, C. E. & M. D. 1932: Herpetological results of the Whitney South Sea Expe­ dition. VI. - Bull. Amer. Mus. Nat. Hist. 63 : 461-597. F orcart, L. 1951; Nomenclature remarks on some generic names of the snake family Boidae. - Herpetologica 7 ; 197-199. K in gh or n, J. R. 1928: Herpetology of the Solomon Islands. - Rec. Austr. Mus. 16 : 123-178. L aird, M. & E lizabeth L aird 1956: Account of a visit to Bellona and Rennell in August, 1953. - The Natural History of Rennell Island, British Solomon Islands 1 : 65-71. M ayr, E. 1931: Birds collected during the Whitney South Sea Expedition. XIII. A systematic list of the birds of Rennell Island with description of new species and subspecies. - Amer. Mus. Nov. 486 : 1-29. M ertens, R. 1934: Die Inselreptilien, ihre Ausbreitung, Variation und Artbildung. - Zoologica, Stuttgart 84 : 1-209. M ittleman, M. B. 1952: A generic synopsis of the lizards of the subfamily Lygoso- nfinae. - Smithsonian Misc. Coll. 117 : 1-35. O liver, J. A. & C. E. S haw 1953: The amphibians and reptiles of the Hawaiian Islands. - Zoologica, New York 38 : 65-95. P a r k e r , H. W. 1939: Reptiles and amphibians from Bougainville, Solomon Islands. - Bull. Mus. Roy. Hist. Nat. Belgique 15, 60. ‘ . P e te r s , J. A. 1948: A new snake of the genus Tvphlops from the Solomon'^ Islands. - Occ. Pap. Mus. Zool. Univ. Mich. 508 : 1-3. Rcx)iJ, N. E. DE 1915: The reptiles of the Indo-Australian Archipelago. I. Lacertilia, Chelonia, and Emydosauria. - Leiden. - 1917; Ibidem. II Ophidia. - Leiden. Roux, J. 1913: Les reptiles des Nouvelles Hebrides et des lies Loyalty. - In Sarasin & Roux's Nova Caledonia. A. Zoologie 1 : 79-152. Schm idt, K. P. 1932: Reptiles and Amphibians from the Solomon Islands. - Field Mus. Nat. Hist. Chicago Zool. 18 : 175-190. Slevin, j. R. 1934: The Templeton Crocker Expedition to Western Polynesian and Melanesian Islands, 1933. No. 15. Notes on the reptiles and amphibians, with description of a new species of . - Proc. Calif. Acad. Sci. (4) 21 : 183-188. Smith, M. A. 1926: Monograph of the Sea-Snakes ('//iY//-o/7/;//rf^7ej. - British Museum, London. Stull, O. G. 1935: A check list of the family Boidae. - Proc. Boston Soc. Nat. Hist. 40 : 387-408. T anner, V. M. 1948: Pacific island herpetology. No. 1. Mariana Islandf. - Gt. Basin Naturalist 9 : 1-20. - 1951: Pacific Islands herpetology. No. 5 , Solomon Islands: A checklist of species. - Gt. Basin Naturalist 11 : 53-86. W olff, T. 1955a: 1. Introduction. - The Natural History of Rennell Island, British Solomon Islands 1 : 9-31. - 1955 b: 2. Account and list of stations of the Danish Rennell Island Expedition, 1951.-Ibid. 1 : 33-41. - 1955c: 4. Rennellese names of animals. - Ibid. 1 : 59-63.