Xerolinus camanoensis Hart and Ivie, 2016

Hart, Charles J. & Ivie, Michael A., 2016, Two New Species ofXerolinusIvie and Hart (Coleoptera: Tenebrionidae: Opatrini) from Jamaica and the Virgin Islands, The Coleopterists Bulletin 70 (4), pp. 885-891 : 885-891

Xerolinus camanoensis Hart and Ivie , new species ( Figs. 1–5 )

Type Material. HOLOTYPE: Male. BR. VIRGIN

IS: Great; Camanoe, Cam Bay, 100ft; 11JULY1994,

885

M. Ivie; S. Bucklin & M. Becker ; under cacti & rocks/ WIBF 036261 (from WIBF, deposited in NMNH). PARATYPES (12 specimens): 2 ♂♂ and 4 ♀♀ sharing the same label data as the holotype ( WIBF 036262 – 036267 , WIBF) . BR. VIRGIN IS: Great ; Camanoe, Cam Bay; 11 JULY 1994, 100ft; M. Ivie, S. Bucklin &; M. Becker, leaf litter (2 ♂♂, WIBF 035408 and 036268, WIBF) . BR. VIRGIN IS: Great ; Camanoe, Cam Bay, 100ft; 11JULY1994, M. Ivie; S. Bucklin & M. Becker; Berlese litter/ WIBF 036269 (1 ♂, WIBF) . BR. VIRGIN IS:; Great Camanoe , 11JULY; 1994, M. A. Ivie, M. S., Becker, & S. A. Bucklin; dry forest litter/ WIBF 025001 (1 ♀, WIBF) . BR. VIRGIN IS:; Gt. Camanoe Is.; Low Bay , 0-550ft; 17 OCT 1994; M. A. & L. L. Ivie / WIBF 023062 (1 ♂, WIBF) .

BRITISH VIRGIN IS.:; Great Camanoe Is.,; Lee Bay isthmus.; Under rocks in woods.; 19 March 1974; leg. C.L.Remington; & Lawerence Jacob III/ WIBF 009539 (1 ♀, PMNH) .

Diagnosis. This species is distinctive in the combination of its smooth pronotum and elytra, especially convex and dome-shaped profile, and relatively large size (6.2–7.0 mm). The habitus alone will distinguish it from all described Xerolinus species as well as all undescribed ones known to us. The male genitalia will futher distinguish this species. It is the only known species of Xerolinus in the Virgin Islands.

Description. Male. Length 6.2–7.0 mm, width 3.3–3.5 mm. Body: Dull black ( Fig. 1 ), except

8 th striae visible in lower right; 3) Abdominal ventrites; 4) Aedeagus, dorsal view; 5) Aedeagus, lateral view.

last 3 antennomeres testaceous, sometimes almost golden (dependent on preservation); elongate oval; highly convex; almost entirely lacking setae dorsally. Head: Epistoma strongly emarginate; finely punctate ( Fig. 1 ), each puncture about 1/2 as large as an eye facet medially, separated by approximately 1–2X puncture diameters; size and distribution regular. Antennae clavate. Dorsal and ventral portions of eye roughly equal in size and shape. Gular horns prominent. Pronotum: Gradually widened posteriorly ( Fig. 1 ); apical margin evenly, broadly emarginate; apical angles rounded; width at base less than width across humeri; basal margin bisinuate; dorsal surface broadly, evenly convex; all margins narrowly beaded, except obsolete at middle of anterior and posterior margin; minutely punctate, puncture diameter half that of punctures on head. Hypomeron feebly rugulose, shallowly and sparsely punctate. Scutellum: Small, triangular, slightly wider than long ( Fig. 1 ). Elytra: Broadening from base to widest point opposite abdominal ventrite 2, then evenly arcuate to apices ( Fig. 1 ); entire surface smooth; striae faint, smooth; strial punctation absent except in anterior half of lateral stria. Interior of elytron ( Fig. 2 ) displays 7 th stria joining 8th stria before humeral angle. Mesoventrite: Somewhat punctate. Metaventrite: Short, punctate, with few short setae. Legs: Ssurfaces setose and finely punctate ( Fig. 1 ). Protibia narrow, expanding gradually distally; posteroventral surface with stout spines; apex obliquely truncate, ringed by stout spines. Protarsus with tarsomeres 1–3 expanded, ventrally with golden, densely setose pads, tarsomere 2 widest, more than 2X width of tarsomere 4. Mesotarsus with tarsomeres 1–3 weakly expanded, ventrally with densely setose pads. Metatarsus narrow, about 2/3 as long as metatibia, without setose pads; 1 st tarsomere more than 2X length of 2 nd. Abdominal ventrites: Smooth; minutely, sparsely punctate, except ventrite V with larger punctures; intercoxal process broadly rounded ( Fig. 3 ); ventrites I–III slightly concave medially; ventrite V flattened medially, posterior margin evenly rounded. Aedeagus: Basal piece and parameres strongly arched dorsally, parameres weakly undulate in lateral view ( Fig. 5 ); in dorsal view, parameres subparallel for basal 2/3, then widening slightly before bluntly rounded apices ( Fig. 4 ); less than 1/3 elytral length.

Female. Length 6.3–7.0 mm, width 3.3–3.7 mm. Similar to male except body typically slightly wider than male. Protarsi and mesotarsi not expanded. Abdominal ventrites 1–3 slightly convex.

Biology. Adults have been collected under cacti, rocks, dry forest leaf litter, and from Berlese leaf litter samples in dry tropical thorn scrub forest.

Distribution. This species is apparently endemic and restricted to Great Camanoe Island (Map 1) in the British Virgin Islands, an island located at 18°28′ 25′′N, 64°31′58′′W.

Etymology. This species has been given the name camanoensis after the type locality, where it is apparently endemic.

Discussion. This is a remarkable species, endemic to a tiny island surrounded by seemingly suitable habitat on all sides (Map 1). One of us (MAI) started the Beetles of the Virgin Islands project in 1978, and over the years he and his collaborators have collected hundreds, maybe thousands of blapstinoids from 24 islands of the US and British Virgin Islands that lie on the Puerto Rican Bank (see Ivie and Hart 2016, table 1). Hundreds of additional specimens from the Virgin Islands in various museums have been examined, some dating back to the late 18 th century. In the early 1980s, MAI received a loan of a single specimen of a very unique species from the PMNH that was labeled Great Camanoe Island, a small private island in the British Virgin Islands. Clearly undescribed, MAI suspected it was mislabeled. The six other blapstinoid species known from the northern Virgin Islands were all widespread among the islands of the Puerto Rican Bank, five of them reaching the main island of Puerto Rico, the sixth making it to Vieques ( Hart and Ivie 2016; Ivie and Hart 2016). One of these species, Diastolinus clavatus Mulsant and Rey , has been known from the Virgin Islands since its description in 1859. It is so ubiquitous that it serves as one of the surrogates to check for Virgin Islands holdings in other collections. It is known from 23 islands from Puerto Rico to Anegada ( Hart and Ivie 2016), but no Great Camanoe record was known. The idea that the only specimen known from an island in such a well-sampled area would be something new was very suspicious.

The northern Virgin Islands (not including St. Croix) lie on the Puerto Rican Bank, and were all joined as a single island stretching from Anegada to Puerto Rico during the eustastic minima of the Pleistocene, 18,000 years ago (Heatwole and MacKenzie 1967; Heatwole et al. 1981; Fairbanks 1989). Based on water depths, Great Camanoe has only been an isolated island for about 11,000 years ( Fairbanks 1989). After exhaustive collecting on several islands within sight of Great Camanoe over 15 years, no other specimen of this species was taken. Guana Island, 2 km to the west, is coleoptereologically perhaps the most extensively sampled of any West Indian island ( Lazell 2005; Valentine and Ivie 2005) and has five known blapstinoid species. Beef Island, 0.8 km to the south, is less sampled, but has a D. clavatus record. Tortola, 2 km west-by-southwest, is likewise well sampled, with four known species. Even tiny, ecologically devastated Marina Cay , 300 m east, has a D. clavatus record. All these neighboring

Map 1. The Eastern Islands Group of the Tortola Sister-Islands. Map is centered on 18.54°N, 64.54°W. From IRF

(2015), used with permission.

islands were joined in the same island 11,000 – 18,000 years ago, and the expectation is that they would share most of the common members of the fauna. In none of these samples, nor any of those from further afield on the Bank, were there specimens of this new, unique species. However, MAI felt that before declaring the PMNH singleton as mislabeled, he should at least make one attempt to find it. After all, he knew very well how to collect this group. So, at 9:30AM on 11 July 1994, a small boat took him and two students to the dock on Great Camanoe, and they proceeded to search for it before returning to Guana Island for lunch. Within five minutes of landing, specimens were found under cut pieces of dildo cactus ( Pilosocereus royenii (L.) Byles and G. D. Rowley; Cactaceae ) lying on dry, sandy, rocky ground, the most expected place for a blapstinoid to be found. Over the next three hours, the group collected another 11 specimens, in the most expected situations, as well as two other species of the widespread blapstinoids known from surrounding islands, D. clavatus and Platylus dilatatus (Fabricius) . On 17 October 1994, MAI and three others returned, again between breakfast and lunch, and found one more specimen. Guana Island has literally thousands of person-hours of handcollecting by a dozen entomologists and many years of pitfall effort, and no sign of this species has been seen. By comparison, Great Camanoe had 21 person-hours of collecting effort with a yield of a dozen specimens of the new species.

No other species of the West Indian endemic genus Xerolinus is known from anywhere else in the Virgin Islands, indeed nowhere else east of mainland Puerto Rico, where an undescribed, but not terribly similar, species occurs. Scrub Island (Map 1) lies 200 m to the east and has never been sampled, and a few other very small unsampled Cays, notably Little Camanoe, lie between Great Camanoe and Beef Island. These islands should be sampled.

At the time of the visits in 1994, access to Great Camanoe’ s dock was by landowner permission only, and the island is totally privately owned. But since that time (1999), the 20-ha (land portion) Cam Bay National Park has been established, making protection of this remarkable species more likely ( IRF 2015).

As part of the study that resulted in Hart and Ivie (2016) and Ivie and Hart (2016), thousands of blapstinoids from more than two dozen museums and collections were assembled from over 100 West Indian Islands, and nothing approaching the morphology of this species was seen from other islands, making the chance that it is introduced small. This possibility, of course, cannot be totally eliminated, but we feel it unlikely.

Still, the concept of a relatively large, and easily found, endemic beetle being so restricted is unexpected. It is not like other known singleisland endemics in the Virgin Islands that have close relatives on surrounding islands (MAI, unpublished data). Xerolinus camanoensis is the only member of its genus found in the Virgin Islands and deserves more study. There is nothing that is regionally unique about Great Camanoe ( IRF 2015). At 337 ha and with a maximum elevation of 168 m, it is about 4 km long and 1 km wide. This is large enough to support a relatively large number of individuals, but why X. camanoensis would occur only there is a great mystery.

Figures

Figs. 1–5. Xerolinus camanoensis. 1) Dorsal habitus; 2) Interior of elytron, elytral suture top, junction of 7th and