Hypogeophis brevis Boulenger, 1911

Gower, David J., 2017, A new species of small and highly abbreviated caecilian (Gymnophiona: Indotyphlidae) from the Seychelles island of Praslin, and a recharacterization of Hypogeophis brevis Boulenger, 1911, Zootaxa 4329 (4), pp. 301-326 : 303-313

Hypogeophis brevis Boulenger, 1911

( Figs. 1–6 ; Table 1)

Lectotype. BMNH 1910.3.18.84 (also numbered 1946.9.5.24: Fig. 2 ) from West side of Morne Seychellois, Mahé, 1,200 feet ( Boulenger 1911), designated by Taylor (1968: 755).

Paralectotype (n = 1). BMNH 1910.3 .18.85 (= 1946.9.5.25) from Cascade, Mahé ( Boulenger 1911) . Cascade is the name of a district in Mahé as well as a village, river, forest and estate within this district . Cascade district ranges from sea level to over 600 m elevation and we suspect (based on the boundary of Cascade district and all other known localities for H. brevis ) that the specimen came from above 350 m somewhere between the La Misère and Montagne Posée roads that cross the island between the East and West coast.

Referred specimens (n = 39). See Appendix 1.

Diagnosis. Hypogeophis brevis differs from H. rostratus in having secondary annular grooves on most primary annuli (versus on only posteriormost primary annuli) and in having fewer than 95 vertebrae (Parker, 1958). Hypogeophis brevis differs from H. pti sp. nov. in having more vertebrae (71–75 versus 67–69 in known specimens) and in having tentacular apertures relatively further from the eyes and closer to the nares (E-TA/E-N> 0.75 versus <0.65. Hypogeophis brevis differs from species of the other Seychelles indotyphlid genera ( Praslinia , Grandisonia ) in having tentacular apertures anterior to the mouth (on that part of the snout overhanging the lower jaw) and tentacular grooves covered by bone.

New description of lectotype. Our evaluation of the lectotype is consistent with the accounts given by Boulenger (1911) and Taylor (1968), but those were both very brief hence a more detailed description is provided here. Some meristic and morphometric data are given in Table 1. Condition poor to moderate; stiffly dehydrated, especially anteriorly where there is a deep, broad midventral groove; specimen broken in two parts, anterior part longer; ca. 45 mm ventral incision into coelom extending forwards from behind disc; head and anterior of body (approximately over 10 PAs) downturned; jaw articulation broken at CMs, inside of mouth damaged; stratum corneum missing on parts of head and scattered small patches of body; skin over right eye partly reflected; some scale pockets partially opened dorsally.

interrupted by vent and disc; AG_antvent = incomplete AGs immediately anterior to vent and disc; AG_incomp = incomplete AGs in vicinity of vent and disc; LT = tip of lower jaw; MC = midbody circumference; PAG_SAG = PAGs anterior to first SAG; PAG_SAGd = PAGs anterior to first dorsally complete SAG; PAG_SAGv = PAGs anterior to first ventrally complete SAG; = Total length; WH = maximal width of head; WM = width at midbody. See Materials and Methods for other abbreviations. Values separated by comma are given in left, right order. * indicates lectotype, # indicates paralectotype. Tooth counts in parentheses are from x-ray CT reconstructions.

1910.3.18.84 1910.3.18.85 UMMZ UMMZ UMMZ UMMZ 2005. 2005. UMMZ UMMZ Specimen * # 180853 183066 189441 221084 1793 1929 168115 189442 - 4(4) - 5(4) 4(4) - - - - 6(6) 5(5)

…….continued on the next page UMMZ UMMZ UMMZ UMMZ UMMZ UMMZ UMMZ UMMZ UMMZ 2005. 2005. Specimen 146295 175435 180852 181384 181385 182998 192977 200520 175493 1781 1786

F F F F F F F F F? M M Vertebrae 71 71 75 73 75 73 72 73 71 72 71 Fresh mass (g) - - - - - - - - - 3.4 1.8 Fresh TL - - - - - - - - - 124 104

103 91 77 86 91 71 78 98 65 107 95

23 18 17 16 17 13 - 18 12 23 19 WM 6.6 4.8 3.7 4.5 5.1 3.8 - 5.7 3.1 5.3 5.8 ST-NG1 4.3 4.2 3.4 3.9 4.1 3.7 3.9 4.0 3.5 4.3 4.0 LT-NG1 3.3 3.2 2.8 2.9 3.1 2.9 3.1 3.0 2.6 3.3 3.2 ST-AM 1.1 1.1 0.9 1.0 1.1 1.0 1.0 1.0 1.0 1.1 1.1 WH 3.0 2.7 2.5 2.5 2.6 2.3 2.6 3.0 2.2 3.2 2.9

1.7 1.6 1.4 1.5 1.6 1.4 1.5 1.6 1.3 1.7 1.5 2005. 2005. 2005. UMMZ UMMZ UMMZ UMMZ UMMZ UMMZ Specimen 1787 1789 1791 145180 180854 180855 182999 193089 189440

M M M M M M M M M? Vertebrae 71 73 72 72 72 72 72 71 73 Fresh mass (g) 2.7 0.4 0.4 - - - - - - Fresh TL 125 73 68 - - - - - -

109 62 58 77 96 93 86 74 45

20 11 12 17 16 17 15 18 9

5.7 3.1 3.4 4.1 5.1 5.3 4.3 4.1 2.4 ST-NG1 4.4 3.5 3.4 3.6 4.0 3.9 4.0 3.7 3.3 LT-NG1 3.5 2.7 2.6 2.8 3.0 3.0 2.9 2.9 2.5 ST-AM 1.1 1.0 0.9 1.1 1.0 1.1 1.0 1.0 0.9

3.1 2.1 2.3 2.6 2.9 2.6 2.7 2.5 2.1

1.8 1.3 1.3 1.4 1.6 1.5 1.5 1.5 1.2

0.7 0.6 0.6 0.7 0.6 0.6 0.5 0.5 0.5

1.9 1.5 1.4 1.6 1.9 1.7 1.7 1.6 1.3 E-TA 1.5 1.2 1.1 1.4 1.6 1.5 1.5 1.4 1.0 E-TA/E-N 0.79 0.80 0.79 0.88 0.84 0.88 0.88 0.88 0.77 TA-N 0.2 0.3 0.3 0.2 0.3 0.2 0.2 0.2 0.3 length 1.3 1.1 1.0 1.0 1.1 1.2 1.2 1.1 0.9 length 2.0 1.2 1.1 1.3 1.8 1.5 1.4 1.7 1.0 TA-TA 1.0 1.0 0.9 1.0 0.9 1.0 1.1 1.0 1.0 on C2 1 1 1 1 1 1 1 1 1 vent-TT 1.3 0.9 0.9 1.3 1.4 - 1.1 0.6 0.8 PAGs 65 66 66 67 67 65 66 66 67 _SAG 1 5 5 0 0 0 0 0 0 _SAGd 7 23 20 8 12 11 9 9 13 _SAGv 21 27 25 15 25 22 22 19 8 _vent 1 0 1 1 1 - 1 1 2 _antvent 1 1 1 2 1 - 1 2 1 _incomp 2 1 2 3 2 - 2 3 3

34(32) - - - - - 30(30) - -

28(22) - - - - - 27(28) - -

26(23?) - - - - - 24(26) - -

6(6) - - - - - 6(6) - - Dorsoventrally compressed; posterior half of body uniform except for tapered last ca. 10 mm; anterior half of body tapering more gradually anteriorly, perhaps artefactually in association with greater dehydration. Head small; head length less than midbody width, head width much less than (approximately half of) body width. In dorsal view head strongly V-shaped, sides straight and converging substantially from back of head to TPs (low bulge on right, barely visible on left), ending in rounded snout tip. In ventral view lower jaw and upper lip about as rounded as snout tip. In lateral view upper and lower lips straight; snout very prominent in lateral view, projection anterior to mouth one half to two thirds as long as upper lip.

Eye clearly inset from edge of head in dorsal view (by slightly more than diameter of eye); faintly visible as dark spot (less clear on damaged right); larger than TAs and TPs; approximately halfway between NG1 and ST. TAs below imaginary lines between nares and CMs; closer to imaginary lines between eyes and nares than to underside of snout; distinctly closer to nares than to lip. In lateral view, CMs closer to bottom than top of head (a little less than twice as far from top than bottom). Nares oval, in lateral view approximately equidistant from top and bottom of snout (very slightly closer to top), slightly closer to tip. In dorsal and ventral views nares not visible. TPs visible in dorsal (not on left) and ventral views, TAs approximately twice as far from AM than from ST, visible ventrally, not visible dorsally.

IMs missing crowns, all other teeth bicusped where visible. Small gap in VP series immediately anterior to choana on right but no definitive diastema between vomerine and palatine teeth. AM-ST a little more than three times the distance between PM and VP series anteromedially. Palate not strongly concave transversely, soft tissue extensively damaged. Tongue damaged anteriorly, one large posterior and far lateral groove on each side. Narial plugs large but not prominent, with delimiting grooves (continuous with lateral tongue grooves) medially. Choanae broadly oval, interchoanal distance a little more than one times the width of each choana (choanae artefactually enlarged due to loss of some palatal mucosa), valves not deeply set. Palate slightly darker than rest of mouth, possibly due to dark lining of olfactory chambers visible through palatal bone, more apparent where skin missing.

Nuchal region much more massive than back of head and anterior PAs. C1 slightly longer than first PA, distinctly shorter than C2. NG1, NG2 and NG3 clearly marked and complete (though NG3 misaligned on left lateral surface). NG1, NG2 and NG3 orthoplicate. One TG clearly indicated on C2, extends across most of dorsum, visible in lateral view.

AGs moderately conspicuous to naked eye, visibility possibly slightly enhanced by dehydration, especially anteriorly; under microscope well marked throughout. All PAGs except last complete. Anteriormost SAG dorsolaterally on 6th PA, SAGs middorsally complete from 15th PA, midventrally complete on 23rd PA. PAs generally longer anteriorly than posteriorly but this is likely artefactual because body anteriorly is more dehydrated and curved, and anterior PAs are not notably longer in more recently collected specimens. Macroscopically AGs appear as pale lines; under microscope each AG with irregular row of closely packed, pale, small and larger glands posterior to narrow darker band. Posterior edges of annuli increasingly raised far posteriorly, thin whitish line appears between darker band and paler glands, whitish line not visible on anterior one quarter of body and inconspicuous posteriorly.

Posteriorly (within 15 AGs from TT) three rows of scales in pockets as deep as approximately two thirds to three quarters the length of a PA at this point; anteriorly (15 PAGs behind collar region) one or two scale rows in pockets approximately one third the length of a PA. All observed scales oval, wider than long.

Large terminal cap approximately 1.75 times length of adjacent PAs. Posteriormost AG extends from right of midline on venter, immediately anterior to disc, around to left of midline dorsally, incomplete laterally (and ventrally) on left, dorsal part of this groove approximately level with front of disc. No AGs on venter behind front of disc. Terminus bluntly rounded, slightly damaged posteroventrally. Disc damaged, slightly wider than long, with nine or 10 denticulations (four posterior, two lateral, three or four anterior) ( Fig. 2 ).

Body dark brown to brown-grey in preservative, paler on more dehydrated anterior half, somewhat paler ventrally with transition lying more dorsolaterally than laterally. Disc and denticulations entirely pale. Head greyish above. Faint, slightly pale patches encircle eyes and extend forwards as eye-tentacle stripes, fading out before reaching TPs. ST unpigmented, pale dorsally; underside of rostrum pale anteriorly, greyish posteriorly; nares and TPs within pale region of ST. Pale upper and lower lip lines. Broad pale regular stripes on lateral and ventrolateral surfaces of mandibles continuous with pale lips.

Variation and additional information. 39 referred specimens plus paralectotype, condition generally good. Rostrum slightly damaged in BMNH 2005.1785, UMMZ 145023, 180852, 200520. Vent region has been removed in UMMZ 146295, 180855, 191384, and in UMMZ 200520 the tail is slightly squashed. These specimens agree with description of lectotype presented above with following exceptions (see Table 1 for variation in quantitative characters).

Sides of head in dorsal view not straight but with bend at point level with anterior of mouth, with rostrum more parallel sided in many specimens (e.g. BMNH 2005.1785, BMNH 2005.1788, BMNH 2005.1790, and UMMZ 168115, UMMZ 180852, UMMZ 200520). Anterior of lower jaw more acute than snout tip in several specimens (e.g. UMMZ 168115, UMMZ 181385, UMMZ 189442); more broadly rounded than snout tip in few specimens (e.g. UMMZ 145034). In lateral view upper lip slightly concave in several specimens (e.g. BMNH 2005.1785, BMNH 2005.1786, BMNH 2005.1793, UMMZ 145180, UMMZ 200520); lower lip downturned in some specimens (e.g. BMNH 2005.1785, BMNH 2005.1788, BMNH 2005.1790, UMMZ 181384). In lateral view, naris approximately equidistant from top, front and bottom of snout in many specimens ( Fig. 4 ). TA on imaginary line between CM and naris in UMMZ 145180; as close to underside of snout as to imaginary line between eye and naris in UMMZ 180852.

All teeth are bicusped as far as determined. No obvious differences in sizes of teeth in different rows. PM row extends to just past the choanae, VP row extends a little further (3 or 4 loci) posteriorly. Occasional gaps but no diastemata in teeth series. Choanae approximately level with eyes. Tongue with bluntly rounded unattached tip and paired narial plugs, which may be quite low or a little raised, with an encircling groove that may or may not be continuous with a posterior lateral groove. Dark pigment sometimes present on the tongue and palate but highly variable, pigmented narial plugs sometimes with whitish apices. Choanae subcircular to oval with superficial (visible), somewhat oblique, valves. Interchoanal distance varies from approximately 1.5 to 2.5 times the width of a choana.

NG1 anteriorly concave dorsally in UMMZ 175493 and posteriorly concave ventrally in UMMZ 168115; NG3 more or less orthoplicate in UMMZ 145023. NG3 midventrally incomplete in five specimens, four from La Reserve (BMNH 2005.1788, BMNH 2005.1790, BMNH 2005.1789, BMNH 2005.1793) and one from below Congo Rouge (BMNH 2005.1784). Collars no greater in girth than back of head in a few specimens (e.g. BMNH 2005.1929, BMNH 2005.1793). In UMMZ 182998 small additional TG between TG and NG3. C2 with three evenly spaced TGs in UMMZ 180852, UMMZ 181383, UMMZ 183066 (central TG most extensive).

PAs longer anteriorly than posteriorly in UMMZ 193089, UMMZ 181385, possibly caused by differential dehydration along length of body. Posteriormost AG confined to narrow portion of dorsum in a few specimens (e.g., BMNH 2005.1786, BMNH 2005.1788, UMMZ 183066, UMMZ 192977, UMMZ 200520). Dorsal part of posteriormost AG approximately level with slightly behind the disc surrounding the vent (BMNH 2005.1928, UMMZ 189440), the posterior part of the disc (e.g. UMMZ 14023), or the centre of the vent (e.g. BMNH 2005.1788, UMMZ 193089). Terminal cap varies from a little more than one (e.g., BMNH 2005.1794, UMMZ 180854) to approximately two (e.g. BMNH 2005.1789, UMMZ 183066) times the length of the posteriormost PA. Where the posteriormost AG extends onto the venter it can here lie further anteriorly than the dorsal part of the AG, sometimes extending to the midventer at the anterior edge of the disc surrounding the vent, making the terminal segment appear (in ventral view: e.g. especially UMMZ 175435) somewhat like a terminal shield (sensu Kotharambath et al. 2012). In many specimens the last few AGs barely bend anteriorly on the ventral surface; orthoplicate in some (BMNH 2005.1781, BMNH 2005.1791, UMMZ 182999, UMMZ 193089). Number of posterior AGs bending forwards midventrally range from approximately 6 (BMNH 2005.1789) to approximately 14 (BMNH 2005.1928). ‘Keel’-like line on posteroventral surface of terminus very small to small in some specimens (e.g., UMMZ 182999, UMMZ 145180), not visible in a few (e.g., BMNH 2005.1784, BMNH 2005.1785).

Pale stripe extending anteriorly from eye complete to TA (and merges with pale snout tip) in several specimens (e.g., UMMZ 182999, UMMZ 180555, UMMZ 180852, UMMZ 175435). Except for UMMZ 189442, posterior end of mandibles with greyish band subparallel and adjacent to pale lower lip.

Distribution, natural history, and conservation. Hypogeophis brevis is known only from the island of Mahé, between 4°37’ S and 4°43’ S ( Fig. 1 ) and at an elevational range of approximately 350– 650 m. During approximately 74 person hours of active caecilian fieldwork on Mahé between 2013 and 2015 we encountered 19 H. brevis at five main localities, all by digging. A total of approximately 21 person hours were spent searching for caecilians at Brûlée (585 minutes) and Casse Dents (675 minutes), where seven and two H. brevis specimens, respectively, were found in sandy clay loam soils with large amounts of root matter; pH 4.15–5.85 and 4.92, respectively. Close to Casse Dents, at the base of the trail up to Congo Rouge, five specimens were found in sandy loam or loam soils (pH 3.78–4.5) and inside rotten logs, during 625 person minutes of caecilian fieldwork. At Mares aux Cochons and the path leading up to Mares Aux Cochons from the Chemin le Niol road (= “Mares aux Cochons trail” as reported in Appendix 1), three specimens were found in sandy clay loam soil (p.H 5.09) with large amounts of root matter, during approximately 25 person hours of dedicated caecilian fieldwork. Below Trois Frères during 240 minutes of caecilian fieldwork, two specimens were found in shallow soil on rocky ledges in a gorge a few metres from and above a stream. All these specimens occurred in moist to wet soils under tree cover. Two additional specimens (among unaccessioned material in the Seychelles Natural History Museum; not listed in Appendix 1) were dug from soil on 22 September 2015 at Mares aux Cochons (see Appendix 1) and at 04°37’47.3” S, 055°24’25.8” E, ca. 467 m /asl (field tags MW 10912 and MW 10911, respectively).

Figures

FIGURE 1. Maps showing sampling distribution: (a) Mahé Hypogeophis brevis (grey symbols): circles indicate collecting localities between 2013 and 2015 (BMNH), and triangles indicate approximate collecting localities between 1976 and 1991 (UMMZ), and (b) Praslin H. pti sp. nov. (red symbols).

FIGURE 2. Lectotype of Hypogeophis brevis. (BMNH 1910.3.18.84). Scale bar increments in mm.

FIGURE 3. Twelve referred specimens of Hypogeophis brevis, showing head and collars in dorsal and right lateral views. (a) BMNH 2005.1787, (b) BMNH 2005.1781, (c) BMNH 2005.1786, (d) UMMZ 145180, (e) BMNH 2005.1789, (f) BMNH 2005.1784, (g) BMNH 2005.1788, (h) BMNH 2005.1782, (i) BMNH 2005.1783, (j) BMNH 2005.1793, (k) UMMZ 168115, (l) BMNH 2005.1792. Specimens in (a) – (e) male; (f) – (i) female. Scale bars 2 mm.

FIGURE 4. Twelve referred specimens of Hypogeophis brevis (the same 12 specimens illustrated in Fig. 4), showing posteriormost part of body in ventral view. (a) BMNH 2005.1787, (b) BMNH 2005.1781, (c) BMNH 2005.1786, (d) UMMZ 145180, (e) BMNH 2005.1789, (f) BMNH 2005.1784, (g) BMNH 2005.1788, (h) BMNH 2005.1782, (i) BMNH 2005.1783, (j) BMNH 2005.1793, (k) UMMZ 168115, (l) BMNH 2005.1792. Specimens in (a) – (e) male; (f) – (i) female. Scale bars 2 mm.

FIGURE 5. Hypogeophis brevis, specimens in life collected in 2014 on Mahé from two localities: (a) Casse Dents, specimen BMNH 2005.1984, 1985 or 1986, (b) Brûlée, BMNH 2005.1793.

FIGURE 6. Habitat in which referred specimens of Hypogeophis brevis were found between 2013 and 2015 on Mahé. (a, c) trail to Mares Aux Cochons, (b, d) Brûlée, (e) Trois Freres, (f, g) Mares aux Cochons.