T. F. Hlavac.
A Review of the Species of Scarites (Antilliscaris) (Coleoptera: Carabidae), with Notes on Their Morphology and Evolution.
Psyche 76:1-17, 1969.

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PSYCHE
Vol. 76 March, 1969 No. I
A REVIEW OF THE SPECIES OF SCARITES
(ANTILLISCARIS), (COLEOPTERA : CARABIDAE) WITH NOTES ON
THEIR MORPHOLOGY AND EVOLUTION
BY T. F. HLAVAC~
Museum of Comparative Zoology, Harvard University Recently, through the courtesy of Prof. R. A. Howard, Director of the Arnold Arboretum at Harvard University, the Museum of Comparative Zoology received a shipment of Coleoptera from the Luquillo Mountains of Puerto Rico, collected on "W. Peak" by R. A, McClain. Included in this material was a single specimen of the largest carabid in the Greater Antilles, representing a new species of Scarites (Antilliscaris), 35 mm in length. This behemoth is superficially different from but shares a unique set of characters with two known species of the subgenus from the mountains of Puerto Rico. The presence in the depauperate Puerto Rican montane cara- bid fauna of three species of Scarites raises questions about the ecology and evolution of these beetles. These questions have been approached through study of the comparative functional morphology of S. (Antit- liscaris) and other Scarites subgenera and through preliminary ob- servations and experiments on one adult collected during a recent trip to Puerto Rico.
Banninger (1949, p. 146) proposed the subgenus Antilliscaris for Scarites darlingtoni Banninger, S. mutchleri Banninger (both orig- 'I wish to thank Dr. P. J. Darlington, Jr., for suggesting this study, for advice and encouragement during its progress and for reading the manu- script. I am grateful to Dr. John F. Lawrence for reading the manuscript and for many helpful suggestions. Field facilities at the El Yunque Biological Station of the University of Puerto Rico were provided through the courtesy of Dr. Eric G. Matthews.
Field work on Puerto Rico was supported by NSF Grant GB 7346 to the Committee on Evolutionary Biology of the Department of Biology at Har- vard University.
Published with the aid of a grant from the Museum of Comparative Zoology.




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2 Psyche [March
inally considered to be of uncertain systematic position, 1939, p. 148) and for S. danforthi Darlington. Banninger incorporated the new subgenus into his earlier key to the subgenera of Scarites (1937, pp. 123-128) and provided a key to separate the species. Scarites subgenus Antilliscaris Banninger I 949, p. 136 Diagnosis: head: large, 37-59% of length of elytra. Man- dibles: median carnassal regions large, basal molar area small with complex of interdigitating cusps, dorsal surface smooth. Eyes: small, height 30-50% of height of mandible. Antennae: long to very long for a Scarites, segment 4 similar to apical segments, dorsal and ventral setose areas with rough microsculpture and pair of narrow lateral glabrous regions without setae, sides flattened but not as distinctly as in segments 5-11. Segment 3 circular in cross section with apical ring of setae as well as a number on the apical 2/3 of the dorsal surface and a few setae, including some very large ones on the ventral sur- face (Fig. I 3 ) . Frontal plate grooved. Pterothorax: metasternum and metepisternum short, L/W of episternum 0.87-1.3, elytra fused together and to mesanotum, wings reduced, shorter than metanotum in mutchleri.
Lateral edge of mesotibia with one large spine. Mete- pimeron: slender, pleural suture very faint externally; epimeron-elytra interlocking mechanism absent.
Distribution : montane rain forests of Puerto Rico. Key to the species of S. (Antilliscaris) and to S. ( ?) darlingtoni Banninger
....
Mandibles with series of striations on dorsal surface (Fig. 7) .................................................................................... darlingtoni Mandibles : dorsal surface smooth (Figs. 6, 10, I I ) ................ 2 Elytral intervals I, 3, 5 and 7 with setiferous punctures. Dorsal surface of head with 15 setiferous punctures. Antennae short, ex- tending about to posterior border of prothorax, L/W of segments ........................................... 6-10 less than 1.1 (Fig. 8)
danforthi
Only elytral interval 3 with setiferous punctures. Dorsal surface of head with 6 or fewer setiferous punctures ............................ 3 Antennae extending to mesocoxae, L/W of segments 6-10 between I .3 and I .6 (Fig. 9). Slight impression at posterior end of scrobe. Lateral margin of pronotum with 5-6 pairs of setiferous punc- tures, L/W 0.80. Total length 12-18 mm ................ mutchleri Antennae extending to first abdominal sternite, L/W of segments 6-10 between 1.8 and 2.3
(Figs. 11, 12). Deep pit at posterior
end of scrobe. Lateral margin of pronotum with 3 pairs of seti-



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Figs. 1, 2 -S. (Antilliscaris) megacephalus n. sp. Fig. 3 - S. (A.) danforthi.
Fig. 4 - S. (A.) mutchleri.




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4 Psyche
[March
............
ferou,s punctures, L/W 0.54. Total length 30-35 mm. ......................................................................... megacephalus n. sp. Scarites (Antilliscaris) mutchleri Banninger Scarites mutchleri Banninger 1939, p. 149, replacement name for montanus Mutchler 1934, not montanus Banninger, 1932. Scarltes montanus Mutchler 1934, p. 1.
Type :
American Museum of Natural History, seen ; type locality: Puerto Rico, Luquillo Mtns., El Yunque, 1800 ft. Description (diagnostic characters only). With the characteristics of the subgenus Antilliscaris.
Forms as in Fig. 4. Head: antennae
long, extending to about middle of peduncle, apical segments inter- mediate between danforthi and megacephalus, L/W of segments 4-10 between 1.3 and 1.9 (Fig. 9). Vertex: 3 pair of setae, clypeal, supra- orbital and a pair halfway between the two and closer together than either. Lateroclypeus and antero-lateral halves of vertex with a series of irregular striations. Without a large depression behind the eye and a deep pit at the posterior end of scrobe. Prothorax: lateral grooves narrow but distinct with 5 or 7 pairs of setiferous punctures, posterior angles small. Sternum : 6-8 setif erous punctures clustered in front of the intercoxal spine, the latter with 6-8 setae. Elytra:
surface dull, anterior margin with dense band of coarse tubercles in addition to the tubercles associated with setiferous punctures. Lateral groove: dense concentration of tubercles, 7-8 setiferous punctures on third interval. Striae lightly impressed. Pterothorax: mesasternum, 2 setiferous punctures; metasternum 6-7 setiferous punctures. Ab-
domen: 1st and 2nd intersegmental sutures normal. Measurements.
Head: length 2.7-3. I mm, width 3.6-4.0, length/ width 0.75-0.77. Mandible: length 2.3-3.0. Prothorax: length 3.1- 3.5, width 4.0-4.6, length/width 0.77-0.76. Elytra: length 6.9-7.9, width 4.2-4.8, length/width I .64-I .64. Total length (including peduncle) I 5 .4-I 8.0 mm. Measurements reported: extremes in total length of the four specimens measured. Specimens examined: 11010- type and three others (M.C.Z.). A specimen, currently alive, about 12 mm in total length, has not been examined critically. Distribution: El Yunque, 1800 ft. to summit (3493 ft.). Larva: Three presumably second instar Scarites were collected on El Yunque one in a decayed log in cloud forest c. 2200 ft., and two others under rocks along a forest trail c. 3200 ft. Based on size (head capsule of preserved larve 1.9 mm wide) these larvae are probably mutchleri.
Scarites (Antilliscaris) megacephalus n. sp. Holotype: a male M.C.Z. No. 31710. Type locality: Puerto



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Fig. 5 -Mandibles, S. (s. i.) suhfriuius. Fig. 6- Mandibles, S. (^.) mufcMeri. Fig. 7 - Mandibles, 5. ( ?) dartiwgtoni. Fig. 8 - Antenna1 apex, S. (A.) dunforthi. Fig. 9-Antenna1 apex, S. [A.) mittchleri.



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6 Psyche [March
Rico, Luquillo Mountains, top of West Peak, 3447 ft., May or June 1968, W. C. McClain Coll. Paratype: M.C.Z.; Sex ?, El Yunque c. 3200 ft., Feb. 1969, L. H. Herman Jr., B. C. and T. F. Hlavac collectors. This fragmented specimen, missing the antenna1 flagella, maxillae, several legs and the apical abdominal segments, was collected dead under a stone along a forest trail. Description (diagnostic characters only). With the characteristics of the subgenus Antilliscaris (form as in Figs. I, 2). Head: very large as compared to the relatively squat pronotum and elytra. An- tennae very long, extend to first abdominal sternite, length/width of segments 4-10 between 1.8-2.3 (Fig. 12). Vertex: pair of clypeal and supraorbital setiferous punctures. With a deep, broad depression behind the eye and a deep puncture at the posterior end of the scrobe. Lateroclypeus and antero-lateral halves of vertex with series of ir- regular situations. Prothorax: lateral grooves narrow but distinct with 3 pairs of setiferous punctures (4 on left side of paratype). Sternum without setiferous punctures, intercoxal spine with I 2. Ely- tra: surface dull. Anterior: margin with small number of minute tubercles about 1/3 the width of those associated with punctures; I pair of setiferous punctures in third interval, striae strongly im- pressed. Mesasternum with 2 setiferous punctures, metasternum with 4. Abdomen: lateral portions of 1st and 2nd intersegmental sutures broadened and deepened to form a large fossa, sutures separating other segments slightly enlarged laterally.
Measurments of holotype and paratype: Plead: length 7.5-7.1 mm, width 9.5-7.2 length/width 0.79-0.98 ; Mandible: length 7.0-5.7 ; Prothorax: length 5.5-5.0, width 10.1-8. I, length/width 0.54-0.62 ; Elytra: length I 3.0-12.5, width 9.3-7.9, length/width I .4-I .58 ; Total length (including peduncle) : 35-30 mm.
Distribution: known only from the type series. Scarites (Antilliscaris) danf orthi Darlington Scarites danforthi Darlington 1939, p. 80. Type:
M.C.Z. No. 23,501 seen; type locality: Puerto Rico, Maricao forest, c. 3000 ft.
Description (diagnostic characters only) . With the characteristics of the subgenus Antilliscaris, form as in Fig. 3. 'Head: antennae, relatively short, extend to posterior margin of prothorax, apical seg- ments squat, L/W of segments 4-10 less than 1.1 (Fig. 8). Vertex with I 5 setiferous punctures including 2 pair of supraorbitals. Later- oclypeus and anterolateral halves of vertex without series of irregular situations. Without a large depression behind eye and deep pit at posterior end of scrobe. Prothorax: lateral groove indistinct near



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Fig. 10 -Mandibles, S. (A.) danforthi
FIR. 11 -Mandibles, 5. (A.) megacephlus a, sp. Fig. 12 -Antenna1 apex, S. (A.) rneyucephattts n, sp. Kg. 13-Antenna1 segments 3, 4, 5, 5. <A.) megacephalus n. sp.



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8 Psyche
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middle, with 5 pairs of setiferous punctures, posterior angles very small. Sternum : about 20 setiferous punctures clustered about the midline, intercoxal spine with 10-12 setiferous punctures. Elytra: surface shiny. Anterior margin : small number of minute tubercles 1/3 the width of the tubercles associated with setiferous punctures, 4 or 5 setiferous punctures in first interval, 7 or 8 in third, 6, 7, or 8 in fifth, and 5, 6, or 7 in seventh, striae lightly impressed. Ptero- thorax: mesasternum 8 setiferous punctures, metasternum 6 setiferous punctures.
Abdomen : lateral parts of I st and 2nd intersegmental sutures broadened and deepened to form a large fossa, other sutures enlarged laterally.
Measurements of holotype and paratype. Head: length 2.5-3.0 mm, width 3.1-3.5, lengthlwidth 0.81-0.86. Mandibles: 2.2-2.6. Prothorax: length 2.7-3.0, width 3.9-4.0, length/width 0.69-0.67. Elytra: length 6.7-6.7, width 4.0-4.0, lengthiwidth 1.68-1.68. Total length (including peduncle) I 4.6-1 6.0. Distribution: known only from the type series. Scarites (subgenus ?) ddingtoni Banninger Scar'ites dadngtoni Bann. 1935, p. 159.
Scarites (Antilliscaris) darlingtoni Bann. 1949, p. 137. Type: M.C.Z. No. 21,797, seen. Type locality: N. Haiti, Mt. Basil, c. 4700 ft.
Description (diagnostic characters only). Head: large, 43% of the length of the elytra. Mandibles (Fig. 7) heavily worn in type, with striate dorsal surface and relatively small molar area. Eyes: 5070 of the height of the mandible. Antennae: absent in type. Latero- clypeus and antero-lateral halves of vertex with series of irregular striations.
Vertex: pair of clypeal and supraorbital setiferous punc- tures. Without depression behind eye and large puncture at posterior end of scrobe.
Prothorax: lateral grooves distinct with 7 or 8 seti- ferous punctures.
Sternum: without setiferous punctures but with 17 on intercoxal spine. Elytra: surface polished. Anterior margin with small number of tubercles about 1/3 the width of those asso- ciated with punctures. Lateral groove rugose. 8 setiferous punctures in third interval, striae impressed. Pterothorax: reduced, elytra fused together and to mesanotum, wings shorter than the metanotum. Met- episternum and metepimeron absent in type, L/W about I. Mesa- sternum without setae and metasternum with 6. Abdomen: inter- segmental sutures normal.
Measurements of holotype: Head: length 4.0 mm, width 5.1, length/width 0.78. Mandible: length 3.0. Prothorax: length 4.0, width 5.6, length/width 0.72. Elytra: length 9.5, width 6.3, length/



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19691 H h c - scarites
9
width I 40. Total length (including peduncle) 2 I .8. Specimen ex- amined: holotype.
Comments: known from the appendageless fragments of two speci- mens. I regard it as of uncertain subgeneric position for three reasons. The structures containing the major diagnostic characters of Antit- liscaris, antennae and metepimeron, are absent in the available ma- terial. A major similarity between Antilliscaris and darlingtoni is the reduction of the flight mechanism. Fligh tlessness and, in extenso, large-scale reorganization of the flight mechanism occur with high frequency among montane carabids (Darlington 1943), which argues against uniting darlingtoni with Antilliscaris in the absence of other evidence. Furthermore, there is a. gap between Antilliscaris and dar- Zingtoni in the dorsal surface of the mandibles (Figs. 5, 6, 7, 10, I I ) . DISCUSSION
Several
character states in Antilliscarls range from atypical to unique for a Scarites s. I. Many of these differences are found in the locomotory system or are peripheral to it. This raises questions about associated behavioral and ecological differences. In an attempt to list some of the ~ossible answers to these questions, particular configurations of AntiZliscaris are contrasted with 8. (s. s.) sub- striatus Haldemann and subterraneus Fabricius. This is not done because I feel that these 2 species are closely related to Antilliscaris, but because both fly and burrow (Hlavac, 1967) and can be used as a base line in interpreting the morphology of Antilliscaris. ANTENNAE: The antennae of Antilliscaris are unusual in three respects: in length, in the setation of the 4th segment and in the relative narrowness of the lateral glabrous areas. An increase in the size of the antennae can be documented in terms of elongation of individual segments, as expressed by length/width, and in terms of increase relative to body size. The ranges of length/width of seg- ments 6-10 is 0.9-1. I in danforthi, I .35-I .55 in substriatus, I .3-I .6 in mutchleri, and I 3-2.3 in megacephalus. The antennae reach the procoxae in substriatus, the posterior margin of the prothorax in dan- forthi, and middle of the peduncle in mutchleri and the first abdominal sternite in megacephalus. As compared to substriatus, the antennae of danforthi are longer and the individual apical segments are much wider. Assuming that there are no major differences between the rel- ative widths of the first segment in the above species, then a measure of width of the antenna1 apex can be expressed as width of an apical segment/width of segment I. Using width of the 8th segment in this ratio, the figures are 0.72 for substriatus and megacephalus, 0.93 for mutchleri and 1.1 for danforthi.




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10 Psyche [March
To summarize, the antennae of all Antilliscaris are longer than substriatus. The apical segments are broad in danforthi, elongate in megacephalus, with mutchleri and substriatus intermediate. In substriatus, 28% of the antennae extends beyond the mandible. When burrowing the antennae are held agaist the head wall causing the apical segments to curve in a broad U. In megacephalus 50% of the antennae extends beyond the mandible. If this species burrows the antennae would be doubled over while the animal is working. Short antennae are characteristic of the many diverse taxa of burrow- ing Coleoptera which have independently evolved a pedunculate body form. The long antennae of Antilliscaris and particularly megace- phalus strongly suggests that these beetles do not burrow. Captive s,ubstriatus and subterraneus and many geophilious carabids apparently do not react visually to prey; olfactory and/or tactile reactions have been observed upon physical contact. While at rolling a burrow system, the antennae of subterraneus are held parallel to the long axis; the maximum sweep width is limited by the diameter of the burrow. On the surface, they are held approximately 45O from the long axis. If only short range olfactory and tactile stimuli are used to recognize prey, then finding it will be a function of the distance travelled and the width of the band through which the sensory equipment move. On the surface, long antennae are clearly adaptive in increasing the width of the search band, and may par- tially explain the condition in Antilliscaris. There is a gap in the setation and microsculpture of the first 4 segments as contrasted to segments 5-1 I in all subgenera except An- tilliscaris and Typhloscaris from the mountains of E. Africa. In most subgenera, segments 1-4 have few or no setae and are circular in cross section, while segments 5-1 I are flattened laterally and have a dense covering of setae and rough microsculpture except for a glabrous, asetose median stripe. Segment 4 of Antilliscaris is inter- mediate in shape between segments 3 and 5 and has the surface organization of the apical segments.
The surface of the apical segments is divided into two distinct structural and, probably, functional areas. As seen in lateral view,
a pair of setose bands with rough microsculpture extend along the dorsum and venter of the apical segments; they are united near the distal end of the I I th segment (Figs. 8, 9, 12). Between the setose
bands is an asetose median band with smooth microsculpture. Mem-
bers of the genus Scarites differ widely in the distribution of these two surface types; in S. (Antilliscaris) the median band is 25-30% of the width, but 55% in substriatus.




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19691 Hlavac -- Scar ites I I
The elongate and/or broad apical segments and the state of the 4th segment in Antilliscaris represent an increase in surface area of antenna1 apex over substriatus. Due to differences in distribution of surface types, there is a large increase in setose areas, which can be interpreted as an intensification of the functions served by this region. EYES: The eyes of AntilZiscaris are small, 30~50% the height of the mandible, vs. 100% in substriatus, and are nearly circular except in danforthi where the posterior border is nearly straight. Smith (1964, p. I 16) stated that the eyes of flightless carabids are not reduced, except for cave inhabiting species; this is clearly not the case for montane Scarites or for the montane carabid fauna of New Guinea (P. J. Darlington Jr., personal communication). Eye re- duction in Scarites seems to have come about either from a reduction in diameter (AntiZZiscaris) or from diameter reduction and shortening the anterior posterior axis, giving the eyes of 8. (Ty$hZoscaris) and S. (T'aenioZobus) cubanae Banninger a peculiar slit-like appearance. MANDIBLES: The mandibles of scaritine carabids are structurally complex and can be divided into three functional regions, an apical and 2 medial carnassal areas and a basal molar part. Antilliscaris and Scarites s. s. represent extremes in the relative sizes of the latter 2 of these areas (Figs. 14, I 5). In an unworn specimen of sub- striatus (Fig. s) the apical carnassal is 34%) the median carnassals 26% and the molar 40% of the total length (perpendicular distance between apex and base) ; while in Antilliscaris (Figs. 6, 10, I I ) the apical carnassal ranges from 24-34% the median carnassals from Fig. 14. - Mandibles, 8. (AntiUiscaris). Fig. 15 - Mandibles, 8. (3, s.). Medial carnassal areas shaded.




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12 Psyche [March
45-59% and the basal molar part ranges from 17-21% of the total length. In Antilliscaris then, the median caranassals are twice as large and the molar area half the relative size of the corresponding areas of substriatus.
If it can be assumed that these structural differences correlate with behavioral differences) then the condition in Anti1Ziscari.r may reflect 3 types of such differences. The mandibles of substriatus and sub- terraneus are used to loosen material from the head wall of the bur- row, in mating and, of course) in feeding. Some substrate loosened by the protibia is compressed further and compacted into a part of the stable burrow system by the vertex of the head and pronotum (Hlavac, 1967, and unpublished observations). The smaller molar area in Antilliscaris comuld indicate either that these animals burrow through a less dense) more easily compacted) substrate than Scarites s. s. or that they do not burrow at all. Secondly) the differences in mandible morphology may reflect differences in feeding behavior (see comments on body form) below) or mating. FLIGHT MECHANISM: Antilliscaris represents an extreme point in the atrophy of the flight mechanism. The fused elytra are immovably joined to the mesathorax at two points, the posterior part of the mesatergum is tucked around and closely pressed against the anterior contours of the elytral cavity and secondly) the elytral hinge mech- anism is solidly fused to the anterior part of the mesatergum. The volume enclosed by the metathorax is reduced; externally, this is seen most clearly by comparing the relative size of the lateral portion of the sternum and the L/W ratio of the episternum in flying and wingless species. In s,ubstriatus the narrowest lateral part of the sternum is about half the mid-line length and the L/W of the episternum is about 4 whereas in mutchleri the lateral portion is 20% of the mid-line length and the L,/W of the episternum is about I. The central part of the sternum is also shortened in Anti/- liscaris but less dramatically; the mid-line in substriatus is equal to the length of tthe first 3 112 abdominal sternites while in nzutchZeri it is equal to the length of the first 2 2/3 abdominal segments. The vestigial wings of mutchleri are very small (.375 X -100 mm) and circular in cross section in a specimen examined in fluid. In the Scaritini there are usually 3 lateral elytra-thorax and abdo- men interlocking mechanisms,
(Hlavac) unpublished observations.)
The anterior lateral edges of the elytra fit into grooves on the dorsal rim of the mesepisternum, mesepimeron and metepisternum (Fig. I 7). The dorsal part of the metepimeron slopes inwards; the elytra curve slightly outwards at this point and rest on top of the flat surface of



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19691 ~HZavac - Scarites I3
the epimeron. An internal eIytra1 carina extends from just behind the level of the epimeron to the elytral apex and is enlarged pos- teriorly forming the internal plica, The carina rests against the edge of the infolded abdominal sternites. AntiZZiscaris differs from all other subgenera of Sc,arites examined, including many flightless species, in that the dorsal part of the metepi- meson is in the same plane as the episternum and the dorsal groove extends along the epimeron, i. e. the elytra-epimeron interlocking mechanism is absent, becoming part of the elytra-episternum device (Fig. 18).
Fig. 16 - Elytra-metathorax interlocking mechanism S. (s. s.) substriatus Fig. 17 - Elytra-metathorax interlocking mechanism, S. (Antilliscaris) (EC, internal carina of elytra ; Epm3, metepimeron; Eps3, metepisternum ; G, metapleural groove)
In burrowing and substrate dwelling Coleoptera, the elytral in- terlocking mechanisms maintain the structural integrity of the elytra- body joint against the forces generated in moving through a dense material. Lack of an integral portion of this mechanism in AntiZ- Ziscaris can be explained in two, non-mutually exclusive manners. If