Contributions to Zoology, 86 (3) – 2017José A. Jurado-Rivera; Genaro Álvarez; José A. Caro; Carlos Juan; Joan Pons; Damià Jaume: Molecular systematics of Haploginglymus, a genus of subterranean amphipods endemic to the Iberian Peninsula (Amphipoda: Niphargidae)

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Systematics

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Order Amphipoda Latreille, 1816

Family Niphargidae Bousfield, 1977

Genus Haploginglymus Mateus and Oliveira-Mateus, 1958

Haploginglymus geos sp. nov. Jaume and Alvarez

(Figs 4-5-6-7-8-9-10-11-12-13)

 

Material examined. Cueva del Ocho, Cazalla de la Sierra, Seville, Spain. Geos Spelaeological Society Catalogue ref. no.: CLS-12-Geos. Coordinates: (Datum WGS 84) N 38º 2’ 2.36”; W 5º 54’ 58.15”; 346 m above sea level.. Phreatic lake occupying bottom of cave. Holotype: female 7.5 mm, preserved in single ethanol vial [RMNH.CRUS.A. 5072]. Paratypes: 9 females in single ethanol vial [RMNH.CRUS.A. 5073]. About 100 specimens in single ethanol vial deposited at IMEDEA. Collected by G. Alvarez and D. Jaume. Additional material examined: Cueva de Santiago Grande (CLS-2-Geos; cave placed adjacent to Cueva del Ocho). Numerous specimens. Collected by Alberto Tinaut, Virginia Salabert and Mª Dolores Lara. Deposited at IMEDEA.

Diagnosis. Fourth and fifth peduncular segment of antenna about equal in length. Spines on basal endite (=outer lobe) of maxillule coarsely denticulate. Palp of maxilliped ordinary, unguiform, non-spatulate. Carpus of G1-G2 each longer than corresponding propodus. Basis of P5-P7 not expanded, slender, each with overhanging posterodistal lobe. Telson cleft to only one-third of its total length.

Etymology. Species name refers to Geos Spelaeological Society (Seville), whose members explored for the first time the caves where the new species was discovered and collected the first specimens.

Distribution. Known only from phreatic subterranean waters of Cerro de Santiago (Cazalla de la Sierra, Seville; southern Spain). The area is connected hydrographically to the Guadalquivir River basin.

Description of brooding female. Body (Fig. 4) up to 7.6 mm long, anophthalmous, colourless. Head (Fig. 5A) rostrum absent; lateral lobes evenly rounded, slightly produced, each with submarginal row of short sensillae along dorsal margin; antennal sinus hardly excavated. Epimeral plates I-III (Fig. 12A) each with evenly rounded posterior margin and straight distal (= ventral) margin; posterodistal angle not produced, marked with tiny flagellate spine; armature (strong flagellate spines) of distal margin of plates as follows: plate I, naked; plate II, 1 or 2 spines; plate III, 2 or 3 spines. Urosomites I-III dorsolateral armature (Fig. 13A, C) consisting of one (urosomite I) or 2-3 (urosomite II) short, relatively slender spines at each side; urosomite III naked; urosomite I with one (exceptionally two on one side) stout curved strong (“ecdysial”) spine implanted adjacent to insertion of U1, just in front of it (Fig. 13A).

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Fig. 4. Haploginglymus geos sp. nov., brooding female general aspect.

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Fig. 5. Haploginglymus geos sp. nov., brooding female. A, inset of head with right A2 attached, lateral; B, right A1, lateral.

Labrum (Fig. 6A) ordinary, globose. Paragnaths (Fig. 6B) with well-developed inner lobes.

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Fig. 6. Haploginglymus geos sp. nov., brooding female. A, labrum, anterior; B, paragnaths, dorsal; C, left maxillule; D, left maxilla.

Antennule (Fig. 5B) peduncle segments progressively shorter towards distal, relative lengths as 100: 73: 49; proximal segment provided with one (exceptionally two) short flagellate spines proximally on posteromedial surface. Main flagellum about 2.8 times longer than peduncle, distal articles each provided with short simple aesthetasc. Accessory flagellum 2-articulate, shorter than distal segment of peduncle.

Antenna (Fig. 5A) much shorter than antennule (attaining only 49% length of A1). Proximal segment of 5-segmented peduncle swollen; gland cone on second segment slender; third segment with short triangular process protruding on distomedial margin; fourth and fifth segments relative length as 1: 0.96, fourth segment with several spines on medial surface. Flagellum shorter than peduncle.

Left mandible (Fig. 7A) incisor 5-denticulate; lacinia 4-denticulate; spine row comprising 5-6 pappose elements plus three additional shorter ones disposed as collateral row as figured; molar columnar with short, reduced pappose molar seta. Palp 3-segmented, segments progressively longer towards distal; proximal segment naked; middle segment with two (exceptionally three) setae on ventral margin; distal segment with row of 9 to 15 setae along distal half of ventral margin, three longer terminal setae – one of which much stouter than rest –, and two setae (exceptionally one) implanted adjacent to each other proximally on outer surface of segment; anteromedial surface of third segment setulose (not shown in figure, but see Fig. 8A, corresponding to right counterpart).

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Fig. 7. Haploginglymus geos sp. nov., brooding female. A, left mandible, medial; B, inset of distal margin of coxal gnathobase of right mandible, lateral; C, left maxilliped, dorsal (= anterior).

Right mandible (Figs 7B; 8A) incisor 4-denticulate; lacinia bifid, each branch 5- to 9-denticulate; spine row consisting of 4-5 elements plus shorter intercalary elements; molar seta much longer than left mandible counterpart.

Maxillules (Fig. 6C) symmetrical. Coxal endite (= inner plate) finger-like, crowned with two setae; basal endite (= outer plate) with seven stout spines, of which innermost shortest and 4- to 6-denticulate, adjacent spine 3-denticulate, next two spines 2- or 3-denticulate (one exceptionally 4-denticulate), and three outermost spines 2-denticulate. Endopod (= palp) 2-segmented, distal segment with 3-4 terminal setae.

Maxilla (Fig. 6D) ordinary, both endites subequal in length and with armature limited to distal margin; basal endite (= outer plate) with short simple seta implanted subdistally on outer margin, separated from terminal cluster of setae; coxal endite (= inner plate) devoid of oblique “facial” row of setae.

Maxilliped (Fig. 7C) basal endite (= inner plate) subrectangular, with 3-5 flattened, spatulate spines on distal margin; distal half of medial margin with submarginal row of pinnate setae. Ischial endite (= outer plate) rhomboidal, with row of 9-11 spatulate spines along distomedial margin and row of pinnate setae on distolateral margin. Other armature present on endites as figured. Palp (= merus-to-dactylus) ordinary; unguis present, slender, pointed, claw-like, attaining 77 % length of dactylus.

Coxal gills (Figs 9A; 10A; 11A, C) present on G2 to P6, ordinary, sac-like, stalked. Oöstegites (Figs 9A; 11A) on G2 to P5, broad, with sparsely-set short simple setae on distal margin.

Gnathopod I (Fig. 8B) integument of posterior margin on ischium and merus micro-spinulate; merus with strong, long, bended posterodistal seta. Carpus elongate, slightly longer than propodus, provided with oblique patch of setae on medial surface and with five clusters of setae on posterior margin. Propodus (Fig. 8C) sub-chelate, trapezoidal, about as long as broad; palm angle with three flagellate spines disposed as figured (1 on medial side of margin; 2 on lateral side); longest spine very strong, attaining 35 % length of propodus. Posterior margin of propodus with four clusters of setae. Dactylus with single seta on outer margin.

FIG2

Fig. 8. Haploginglymus geos sp. nov., brooding female. A, right mandible; B, G1, medial; C, inset of hand (= propodus + dactylus).

Gnathopod II (Fig. 9A) with integument on posterior margin of merus micro-spinulate. Carpus elongated, about 1.2 times longer than propodus, with well-delimited row (vs. patch on G1) of setae on medial surface; posterior margin with seven clusters of setae. Propodus (Fig. 9B) subsimilar but larger than G1 counterpart, posterior margin with six clusters of setae (vs. 4 on G1); large spine on palm angle attaining 33 % length of propodus.

FIG2

Fig. 9. Haploginglymus geos sp. nov., brooding female. A, G2 with oöstegite partially folded, medial; B, inset of hand (= propodus + dactylus).

Pereiopod III (Fig. 10A) coxa subrectangular, about 1.2 times longer than broad. Nail (= dactylus+unguis) attaining 35 % length of propodus; unguis 58 % length of dactylus (Fig. 10B).

Pereiopod IV (Fig. 10C) shorter than P3 (92 % length of P3, excluding coxa); coxa subquadrate, slightly broader than long, with shallowly-excavated posterior margin. Nail attaining 36 % length of propodus; unguis 63 % length of dactylus (Fig. 10D).

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Fig. 10. Haploginglymus geos sp. nov., brooding female. A, right P3, medial (oöstegite omitted); B, inset of dactylus + unguis, medial; C, left P4, medial (coxal gill and oöstegite omitted); D, inset of dactylus + unguis, medial.

Pereiopods V-VII progressively longer towards posterior, each with sub-rectangular basis showing well-developed posterodistal lobe. Pereiopod V (Fig. 11A) longer than P4; coxa with broad, overhanging anteroventral lobe. Basis 1.8 times as long as broad. Nail attaining 28 % length of propodus; unguis 35 % length of dactylus (Fig. 11B).

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Fig. 11. Haploginglymus geos sp. nov., brooding female. A, left P5, lateral; B, inset of dactylus + unguis; C, left P6, lateral; D, inset of dactylus + unguis; E, left P7, lateral; F, inset of dactylus + unguis.

Pereiopod VI (Fig. 11C) coxa with distinct, evenly rounded anteroventral lobe. Basis twice as long as broad. Nail attaining 33 % length of propodus; unguis 27 % length of dactylus (Fig. 11D).

Pereiopod VII (Fig. 11E) basis 1.8 times as long as broad. Nail attaining 27 % length of propodus; unguis 30 % length of dactylus (Fig. 11F).

Pleopods I-III (Fig. 12B), ordinary, biramous, rami multi-articulate and longer than respective protopod; latter with pair of 5-denticulate retinacles. Exopod slightly shorter than endopod. Endopod with modified, bifid seta proximally on inner margin of proximal article; rest of setae plumose.

FIG2

Fig. 12. Haploginglymus geos sp. nov., brooding female. A, left pleopod II, posterior; B, left epimeral plates I-III, lateral; C, telson, dorsal.

Uropod I (Fig. 13B) almost as long as U3. Protopod longer than rami, lacking basofacial spine; 1 terminal strong flagellate spine at each side; posterolateral margin with 5-7 shorter flagellate spines, and 2-4 similar spines along posteromedial margin. Exopod slightly shorter than endopod, with five (exceptionally 6) terminal spines; 1-2 spines along posterolateral margin and 0-1 spine on posteromedial margin. Endopod with five terminal spines; 2-3 spines along posteromedial margin; posterolateral margin of segment unarmed.

Uropod II (Fig. 13C, D) protopod with two terminal flagellate spines on posterolateral angle and single flagellate spine on posteromedial angle; posterolateral margin of segment with 1-2 flagellate spines; posteromedial margin unarmed. Rami unequal in length, with exopod much shorter than endopod. Exopod about same length as protopod, with five terminal spines and one spine (exceptionally none) about midway on each margin. Endopod with five terminal spines and other 2-3 along medial margin; lateral margin with 0-1 spine about midway.

Uropod III (Fig. 13E) protopod about 1.5 times as long as broad, with 4-6 flagellate spines on distolateral angle and one short spine on distomedial angle; medial margin of segment with 0-2 short flagellate spines. Exopod about 6.4 times as long as broad, 3.7 times longer than protopod; armature consisting of 3-4 clusters of flagellate spines along lateral margin and 4-5 on medial margin distributed as figured. Endopod reduced, scale-like, with two (exceptionally 1 or 3) flagellate spines subdistally on medial margin.

Telson (Fig. 12C) slightly longer than broad, cleft to approx. one-third (34 %) of its maximum length. Armature consisting of 3-4 distal flagellate spines per lobe (exceptionally 5 on one lobe; see Fig. 12C); lateral margins unarmed except in exceptional specimens displaying one flagellate spine on one or both margins (as in Fig. 12C).

 

Male

Unknown.

 

Taxonomic remarks. Haploginglymus geos sp. nov. is the only member of the genus whose telson is cleft only to less than half of its total length (Table 5). Of the five formally described Haploginglymus species, only H. bergae Pretus and Sabater, 1990, and H. morenoi share with the new taxon the display of a G1 carpus that is longer than the corresponding propodus (Table 5). These species share also the relative elongation of carpus of G2 (Table 5). Whereas H. morenoi differs from the new species in the display of an aberrant, spatulate maxillipedal palp, an elongate, slender propodus in both gnathopods, and in the multi-denticulate condition of the spines of the basal endite (= outer plate) of maxillule, differences with H. bergae are subtler, but also consistent. Thus, the spines present on the basal endite of the maxillule aside the innermost one are multi-denticulate in H. bergae whereas only coarsely 2- or 3-denticulate at most in the new species; the epimeral plates are almost unarmed vs. armed in the new species; the telson is cleft to 60 % of its length vs. only cleft to only 34 % in the new species; the oöstegites are hypertrofied vs. of ordinary size in the new species; the U1 protopod displays a single spine on the posteromedial margin vs. 2-4 spines in the new species; the outer margin of the U1 endopod bears one spine vs. none in the new species; and the distal segment of the mandibular palp displays only one proximolateral seta vs. two setae in the new species.

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Table 5. Some features enabling distinction between Haploginglymus species.

Additional relevant differences between the new taxon and the rest of Haploginglymus species are shown in Table 5.

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Fig. 13. Haploginglymus geos sp. nov., brooding female. A, first urosomite with proximal portion of right U1 attached, lateral; B, left U1, posterior; C, second urosomite with right U2 attached, lateral; D, right U2, posterior; E, right U3, dorsal (= posterior).