Haustorius galvezi, Hancock & Wicksten, 2018

Hancock, Zachary B. & Wicksten, Mary K., 2018, Two new species of sand-burrowing amphipods of the genus Haustorius Müller, 1775 (Amphipoda: Haustoriidae) from the northwestern Gulf of Mexico, Zootaxa 4459 (1), pp. 101-127 : 104-113

Haustorius galvezi sp. nov.

Plates 1–5.

Haustorius sp., Shelton & Roberston 1981: 833 –842. Genus two species c, Sweet 1996: 360 –365, figs. 140–142.

Type material: Holotype: Female 3.5 mm; San Luis Pass, Texas, 29.1029° N, -95.0918° W; 11 March 2014 (M.K. Wicksten). Paratypes: Male 4.0 mm, Matagorda Beach, Texas, 28.5505° N, -96.3013° W, 15 June 2017 (Z.B. Hancock). Female 3.5 mm, Surfside, Texas, 28.9444° N, -95.2888° W, 26 October 2008 (A. Witmer). Ovigerous female 4.5 mm, Jamaica Beach, Texas, 29.1897° N, -94.9796° W, 13 June 2009 (A. Witmer). Holotype has been deposited at NMNH, cataloged as USNM #1492387.

Additional material: 146 individuals, Jamaica Beach, Texas, 26 June 2010 (A. Witmer); 195 individuals, Surfside, Texas, 1 July 2007 (A. Witmer); 45 individuals, San Jacinto, Texas, June 2017 (Z.B. Hancock).

Etymology. After Bernardo de Gálvez y Madrid, Count of Gálvez, for whom Galveston Island is named, where this species was first sampled.

Diagnosis. Antenna 1, flagellum with 5–7 articles, accessory flagellum with 3 articles; antenna 2 with 6–7 articles; mandible incisor bifid, with 5–7 accessory blades; mandibular palp, article 3 with 9–12 spines in comb row; maxilla 2, outer plate broad, lunate and subacute distally; maxilliped, outer plate broad, anterior angle acute with tooth-like spines on ½ length of oral margin; coxa 1 wider than deep; pereopod 3 article 5 posterior lobe greater than 1.2x length of anterior margin; pereopod 6, article 4 posterior margin gently rounded distally with 3–5 large spines; pereopod 7 article 5 subtriangular with spines roughly across entire distal margin, posterior margin less than ½ length of anterior; uropod 1, peduncle with 1–2 proximal spines, 2 interramal spines, 1–3 irregular setae; telson with posterodistally produced region bearing all marginal spines, obtusely cleft.

Description. Based on a 4.0 mm female collected at Jamaica Beach, Texas, in June 2009.

Head. Stubby, broadest at base; rostrum blunt, slightly longer than anterolateral apices, extending 1/3 length of antenna 1, peduncle 1; antennal sinuses concave. Eyes large, oval and lacking pigment.

Antenna 1. Peduncle article 1 short, blunt with 11 long plumose setae arranged radially on ventral surface, 2 short penicillate setae ventrodistally, 1 short plumose seta dorsally extending over anterolateral apices of the head; peduncle article 2 slightly longer than peduncle 1, 20 plumose setae across dorsal margin, 11 long plumose setae concentrated at ventrodistal angle, ventral margin bare medially, 3 plumose setae and 5 thin setae on lateral surface; peduncle article 3 roughly ½ length of peduncle article 2, cluster of thin comb setae on lateral surface, and 4 plumose setae at ventrodistal angle; flagellar articles longest proximally, 6-articulate, clusters of setae decreasing in size distally at each segment junction; accessory flagellum 3-articulate.

Antenna 2. Peduncle article 3 stubby, slightly produced ventrodistally with 2 short plumose setae; peduncle article 4 ventrodistally produced forming distal sinus, 2 medial short spines on dorsal margin, cluster of 3 dorsodistal plumose setae and 2 short simple setae, 21 long plumose setae line ventral margin, ventrodistal sinus with 1 short penicillate seta; peduncle article 5 short, slightly produced ventrally, 5 thin setae and 5 plumose setae along distal half of dorsal margin, 7 long plumose setae along ventral process, cluster of thin spines on ventrodistal margin; flagellar articles longer basally, 7-articulate, 3 plumose setae radiating ventrally from junction of first 3 articles.

PLATE 1. Female, 4.0 mm. L) Lateral view of Haustorius galvezi sp. nov.; R) dorsal view of rostrum; A1) antenna 1; A2) antenna 2.

PLATE 2. Female, 4.0 mm. MD) Mandible, with arrow indicated magnified view of accessory blades; LL) lower lip; MX1) maxilla 1, with arrow indicating a magnified view of the apical teeth; MX2) maxilla 2.

Upper and Lower Lip. Labrum broad, apical margin slightly produced. Lower lip, inner lobes elongate, narrow posteriorly and slightly broadening anteriorly, 0.66x length of outer lobes; outer lobes with broad, subrectangular shoulders, anterior margin lined with fine setae, longest and most concentrated medially.

Mandibles. Incisor bifid; left mandible with lacinia mobilis, short, conical; 6 accessory blades, posterior margin serrate; short bifid accessory tooth on anterior margin of molar; molar triturative, 1 setae medially; mandibular palp article 1 short, inconspicuous; palp article 2 with 9 irregularly arranged thin setae; palp article 3 long, narrow, with 9 stout spines in median comb row, 2 thin setae opposite, 12 spines along terminal margin; right mandible like left except without lacinia mobilis.

Maxilla 1. Inner plate narrow, with 7 thin glassy spines and 1 fine setae terminally; outer plate with 11 stout apical teeth, anterior margin densely lined with fine setae; palp article 2 with 7 plumose setae medially on outer margin, 4 plumose setae terminally along with dense cluster of 14 glassy setae; bailer lobe moderately large, densely setose, not extending posteriorly from base.

PLATE 3. Female, 4.0 mm. MXP) Maxilliped; G1) gnathopod 1, with arrow indicating a magnified view of the nail of article 7; G2) gnathopod 2, with arrow indicating a magnified view of the chela.

PLATE 4. Female, 4.0 mm. P3) Pereopod 3; P4) pereopod 4; P5) pereopod 5; U1) uropod 1.

Maxilla 2. Outer plate broad, lunate, densely lined with finely plumose setae along oral margin, aboral margin with fine setae, distal margin subacute; inner plate strongly curled, half the length of outer plate, margins lined with long comb setae.

Maxilliped. Inner plate narrow, 18 inner marginal glassy spines, 2 stout apical spine teeth followed by a cluster of thin spines; outer plate broadest medially and terminating to subacute angle, with row of 13 recurved teeth orally interspersed with continuous row of dense fine setae terminating medially; palp article 1 with 3 fine setae on aboral margin; palp article 2 with expanded lobe distally, densely lined with setae across entire oral margin, aboral margin bare except at distal angle; palp article 3 geniculate, distal margin and apex densely lined with fine setae.

Gnathopod 1. Simple, fossorial. Coxa broad, wider than deep, slightly produced anteroventrally, 4 plumose setae along ventral margin, lower margin with 4 small spines, broadly rounded dorsally; article 2 narrow proximally, slightly curved posteriorly, 5 long glassy setae on posterior margin, anterior margin bare, widening distally; article 3 small with 3 glassy setae on distal margin; article 5 slightly produced posteriorly, margin lined with fine setae, anterior margin with 3 short setae proximally, 1 long and 1 short spine distally; article 6 roughly tear-drop shaped, terminal apex densely setose; article 7 vestigial, forming a posteriorly curved nail.

Gnathopod 2. Minutely chelate. Coxa broad, smooth anteriorly, progressively rounded ventrally, posterior margin semi-straight, 6 plumose setae from medial to anterodistal angle, cluster of small spines along anterior margin of angle; article 2 narrow, straight, anterior margin bare, posterior margin with 7 long setae, cluster of short setae on posterodistal angle; article 3 with a cluster of setae on posterodistal margin; article 4 slightly produced posterodistally with a sharply curved spine on the apex; article 5 with 10 glassy setae on anterior margin, posterior margin densely covered with long setae, cluster of stout, recurved spines posterodistally; article 6 elongate, narrow, distal margin dense with setae; article 7 minute, flexor surface bearing 5 teeth, closing on strongly hooked posterodistal process of article 6 forming minute chela. Female: oostegite short, narrow with 4 spines on terminal apex.

Pereopod 3. Coxa large, semi-lunate, with 1 short spine above anterodistal angle, 4 plumose setae along angle, 4 spines proximal to plumose setae; article 2 with 3 short plumose setae distally on posterior margin, anterior margin bare save for 3 short setae proximally; article 3 with 2 short plumose setae on posterodistal margin; article 4 broad, anterodistal margin slightly produced to form small shelf over article 5, 5 plumose setae along anterior margin, longest distally, posterior margin semi-continuously lined with row of finely pectinate setae, 4 very long plumose setae posterodistally; article 5 with large posteriorly produced cup greater than 1.5x length of anterior margin, stout spines along cup’s border, 3 plumose setae clustered on posterior margin below row of fine setae, small spine group on anterodistal margin; article 6 curled, tear-drop shaped, with 12 spines arranged along the border of the cup. Female: oostegite long, lunate, with 19 long spines, 1–2 small spines between each.

Pereopod 4. Coxa large, slightly oval, covering entire length of article 2, flattened ventrodistally, 9 thin setae along flattened margin, 4 setae on posterior margin; article 2, anterior margin with 3 short setae proximally, posterior margin with 2 plumose setae distally; article 3 with small spine group posterodistally; article 4 broad, subrectangular, with anterodistal process forming blunt shelf over article 5, 6 plumose setae along posterior margin interspersed with small spines, 4 plumose setae along anterior margin, 2 thin spines protruding from anterodistal shelf; article 5 with small posteriorly produced cup, less than the length of anterior margin, border lined with 6 thick, finely pectinate setae and 4 stout spines, anterodistal angle with short curved setae; article 6 slightly curled, 5 stout spines along distal border, 8 fine glassy setae subdistally. Female: oostegite long, slightly lunate with 20 spines, 1–2 small spines between each.

Pereopod 5. Coxa with posterior lobe larger than anterior lobe, lined with fine setae; anterior lobe smooth, bare; article 2 larger than coxa, posterior margin lined with fine setae, anterior margin dense with plumose setae, distal margin rounded along posterior border becoming progressively flattened, medially produced around article 3; article 4 subtrapezoidal, with 6 irregular rows of stout spines on exterior surface, 10 plumose setae along posterior margin, anterior margin densely lined with plumose setae; article 5 with 3 irregular rows of stout spines, 5 plumose setae on posterior margin, 4 plumose setae on anterior margin; article 6 with 4 stout spine groups anteriorly, bare posteriorly, cluster of long spines terminally.

Pereopod 6. Coxa produced posterodistally and lined here with short plumose setae, bare elsewhere, dorsally produced posteriorly; article 2 subquadrate, anterior margin densely lined with fine setae proximally, plumose setae medially and continuous across the subsequent three articles, posteroproximal angle with short plumose setae, bare elsewhere, distal margin slightly curved posteriorly; article 4 subtrapezoidal, anterior margin densely lined with plumose setae, posterior margin gently rounded with 11 continuous plumose setae and 4 spines at the posterodistal curvature, 11 small spine groups across exterior surface, distal margin continuously lined with short stout spines except for small portion of expanded medial margin; article 5 subquadrate with 2 small spine groups on posterior margin, 4 stout spine groups along anterior margin, 2 irregularly spaced spine groups across exterior surface, distal margin lined with slightly curved stout spines except for at deeply produced anterodistal notch; article 6 slender, bare anteriorly, 4 spine groups along posterior margin, 8 stout spines terminally.

PLATE 5. Female, 4.0 mm. P6) Pereopod 6; P7) pereopod 7; U2) uropod 2; U3) uropod 3; T) telson.

Pereopod 7. Coxa subrectangular, with 7 plumose setae posterodistally, bare elsewhere; article 2 greatly enlarged, semicircular, bare posteriorly, anteriorly with dense row of plumose setae, anterodistally with 4 daggerlike spines; article 4 subtriangular, narrowing posteriorly, posterior margin less than ½ the length of anterior margin, anterior margin with 2 spine groups, 4 plumose setae along proximal margin, 2 clusters of spines on posterior margin, one of which is formed on posterodistal angle, 13 small spines line distal margin continuously, broken only at immediate article 5 junction, 6 thin setae posteriorly; article 5 with gently rounded posterior margin studded with 7 spine groups of 3–4 spines each, distinctly produced lobe at posterodistal angle, 3 short spines irregularly line interior border of the lobe, proximal margin bare, posterior margin with 1 spine group of 2 short spines; article 6 roughly ovoid with 3 spine groups on anterior margin, 5 spine groups on posterior margin, apex with 6 spines.

Pleopods. Pleopod 1, peduncle with row of plumose setae on exterior margin, outer ramus with 13 segments, inner ramus with 10 segments; pleopod 2, peduncle bare on interior margin, exterior margin densely lined with plumose setae, outer ramus with 12 segments, inner ramus with 9 segments; pleopod 3, peduncle with long plumose setae on exterior margin, outer ramus with 11 segments, inner ramus with 10 segments.

Uropod 1. Peduncle with 1 short spine proximally, 4 thin setae irregularly along dorsal margin, 2 large spines at base of outer ramus; outer ramus with 3 spine groups on exterior margin, 3 thin setae on interior margin, 8 stout spines terminally; inner ramus with 2 short spine groups and 3 groups of long glassy setae, 8 spines terminally.

Uropod 2. Exterior margin of peduncle with 10 thin setae, interior distal angle with 3 plumose setae; biramous, inner ramus slightly smaller than outer, lined with finely pectinate setae distally; outer ramus with 8 needle-like spines terminally, 6 spines along exterior margin.

Uropod 3. Peduncle short, stout with 8 spines along distal margin; outer ramus 2-articulate, article 1 with small spines on distal margin, article 2 with 7 terminal spines; inner ramus longer than outer, narrow, with 9 long terminal spines.

Telson. Obtusely cleft 1/3 distance to base forming two distinct lobes, posterior margin slightly produced distally, 8 long glassy spines along produced margin, proximolateral lobes strongly produced with 2 large spines exceeding length of telson, 1 short penicillate seta and 1 plumose seta on lateral surface of each lobe.

Intraspecific variation. The number of spine groups on the anterior margin of pereopod 6, article 5 varies between 3–5 with size of specimen. The extent of the posterior curvature of pereopod 6, article 4 is variable, but rarely as pronounced as H. jayneae . Uropod 1 may have a short spine medially in larger specimens.

Color in life. Translucent gray, gonads and viscera visible through exoskeleton. Eyes white.

Ecology. This species was most abundant on protected or relatively undisturbed fine sand beaches, such as

Padre Island National Seashore and Matagorda Beach. This species appears intolerant of mud or sand rich with shell fragments (‘shell hash’). At Sea Rim State Park, TX, this species was collected by Witmer (2011) alongside L. triarticulatus , while the authors found only L. triarticulatus at this location.

Range. Padre Island National Seashore to Sea Rim State Park, TX.

Remarks. Haustorius galvezi sp. nov. is morphologically similar to H. jayneae from the northeastern Gulf, but differs in the number of antenna 1 accessory flagellum articles, mandible accessory blade number, shape of the outer plate of the maxilliped, shape and spination of pereopod 1 coxa, shape and spination of pereopod 6 coxa, curvature of pereopod 6 article 5, plumose setae on posterodistal angle of pereopod 7 coxa, uropod 1 spination, and shape of telson cleft. See Table 1 for a side-by-side comparison of known Gulf Haustorius , and Figure 1 for illustrated differences between H. jayneae and H. galvezi sp. nov.

Figures

FIGURE 1. Characteristic differences between H. galvezi sp. nov. and H. jayneae. A) Left is Haustorius galvezi sp. nov. and right is H. jayneae, curvature and girth of maxilliped outer plate; B) top is H. galvezi sp. nov. and bottom is H. jayneae, width vs. depth of gnathopod 1 coxa; C) top is H. galvezi sp. nov. and bottom is H. jayneae, shape of pereopod 7 coxa; D) top is H. galvezi sp. nov. and bottom is H. jayneae, cleft of telson. Drawings of H. jayneae from Foster & LeCroy (1991).