Quadrula petrina

Texas Pimpleback

FWS Focus

Overview

Characteristics
Overview

This Texas-endemic freshwater mussel species is only known to occur in the Texas Hill Country's Colorado River and its tributaries. Like many other freshwater mussels, the proposed endangered Texas pimpleback has a unique life cycle that requires the use of a host fish, including catfish species, to transform the immature larva stage into a self-supporting juvenile mussel. The species is small to medium in size and has a yellow to tan shell with vague green rays or concentric blotches. The Texas pimpleback's distribution has been relegated to five known populations across 11 counties in central Texas.

Scientific Name

Quadrula petrina
Common Name
Texas pimpleback
FWS Category
Clams
Kingdom

Location in Taxonomic Tree

Identification Numbers

TSN:

Characteristics

Characteristic category

Habitat

Characteristics
Habitat

The Texas pimpleback occurs in medium to large-sized streams and rivers in riffle and run habitats of heterogenous substrates, or sometimes in gravel-filled cracks in the bedrock, often at depths less than 2 meters and arenโ€™t known to tolerate impoundments.

River or Stream

A natural body of running water.

Characteristic category

Behavior

Characteristics
Behavior
Characteristic category

Physical Characteristics

Characteristics
Size & Shape

The Texas pimpleback is a small to medium-sized freshwater mussel with a moderately inflated, subquadrate to suboval shell. The shellโ€™s beaks are full, high and elevated above the hinge line with two to four rows of sculpturing on the umbo. The shell disc typically lacks sculpturing but has parallel ridges along its broadly rounded posterior slope. The interior shell surface, or nacre, is typically white and iridescent. 

Measurements
Length: Approaching 4 in (100 mm)

Color & Pattern

Texas pimpleback's shell colors range from yellow to tan, brown to black and will occasionally have vague green rays or concentric blotches, but these markings are not considered to be diagnostic shell characters. 

Characteristic category

Life Cycle

Characteristics
Life Cycle

The Texas pimpleback, like all freshwater mussels, has an interesting life history. Males release sperm into the water column, which is taken in by the female fertilizing her eggs. The developing larvae are held by the female until they mature and are ready for release. The mature larvae, called glochidia, are released in proximity to a fish host and attach to the hostโ€™s gills or fins. Glochidia that fail to attach to a suitable host or attach to the wrong location will die. Attached glochidia encyst or implant into the host and develop into juvenile mussels over a period of weeks or months. Once fully developed, the juveniles excyst, or break away, from the host and settle on the stream bottom leaving their host relatively unharmed.

Reproduction

Texas pimpleback are considered to be short-term brooders, or tachytictic. It is expected that the species utilizes similar host fishes as those identified for the closely related Guadalupe orb, including channel catfish (Ictalurus punctatus), flathead catfish (Pylodictis olivaris), yellow bullhead (Amerius natalis) and tadpole madtom (Noturus gyrinus). 

Life Span

While no age at maturity information exists for Texas pimpleback, similar species like congeners (Quadrula spp.; now Cyclonaias) and members of tribe Quadrulini have reached a maximum age of 15 to 72 years and 15 to 91 years, respectively.

Characteristic category

Food

Characteristics
Food

Like all other freshwater mussel species, Texas pimpleback are filter feeders that feed and survive on organic particulate matter, bacteri, and algae that are filtered from the water column. Juvenile mussels live in the sediment and most likely feed interstitially rather than from the water column, using the relatively large muscular foot to sweep organic and inorganic particles found among the substrate into the shell opening.

Geography

Characteristics
Range

The Texas pimpleback is endemic to the Colorado River Basin in Texas and has been documented in five populations across 11 Texas counties.

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Timeline

Explore the information available for this taxon's timeline. You can select an event on the timeline to view more information, or cycle through the content available in the carousel below.

15 Items

Listing

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Critical Habitat

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Listing

Dec 15, 2009

Dec 15, 2009 Listing (Substantial)
90-Day Finding on Petitions To List Nine Species of Mussels From Texas as Threatened or Endangered Wโ€ฆ
  • Publication type: 90 day petition finding
Item 1

Listing

Oct 6, 2011

Oct 6, 2011 Listing (Warranted But Precluded)
12-Month Finding on a Petition To List Texas Fatmucket, Golden Orb, Smooth Pimpleback, Texas Pimplebโ€ฆ
  • Publication type: 12m petition finding
Item 2

Listing

Nov 21, 2012

Nov 21, 2012 Listing (Warranted But Precluded: Resubmitted)
Review of Native Species That Are Candidates for Listing as Endangered or Threatened; Annual Noticeโ€ฆ
  • Publication type: 12m petition finding
Item 3

Listing

Nov 21, 2012

Nov 21, 2012 Listing
Review of Native Species That Are Candidates for Listing as Endangered or Threatened; Annual Noticeโ€ฆ
  • Publication type: CNOR
Item 4

Listing

Nov 22, 2013

Nov 22, 2013 Listing (Warranted But Precluded: Resubmitted)
Review of Native Species That are Candidates for Listing as Endangered or Threatened; Annual Noticeโ€ฆ
  • Publication type: 12m petition finding
Item 5

Listing

Nov 22, 2013

Nov 22, 2013 Listing
Review of Native Species That are Candidates for Listing as Endangered or Threatened; Annual Noticeโ€ฆ
  • Publication type: CNOR
Item 6

Listing

Dec 5, 2014

Dec 5, 2014 Listing
Review of Native Species That Are Candidates for Listing as Endangered or Threatened; Annual Noticeโ€ฆ
  • Publication type: CNOR
Item 7

Listing

Dec 5, 2014

Dec 5, 2014 Listing (Warranted But Precluded: Resubmitted)
Review of Native Species That Are Candidates for Listing as Endangered or Threatened; Annual Noticeโ€ฆ
  • Publication type: 12m petition finding
Item 8

Listing

Dec 24, 2015

Dec 24, 2015 Listing
Review of Native Species That Are Candidates for Listing as Endangered or Threatened; Annual Noticeโ€ฆ
  • Publication type: CNOR
Item 9

Listing

Dec 24, 2015

Dec 24, 2015 Listing (Warranted But Precluded: Resubmitted)
Review of Native Species That Are Candidates for Listing as Endangered or Threatened; Annual Noticeโ€ฆ
  • Publication type: 12m petition finding
Item 10

Listing

Dec 2, 2016

Dec 2, 2016 Listing (Warranted But Precluded: Resubmitted)
Review of Native Species That Are Candidates for Listing as Endangered or Threatened; Annual Notificโ€ฆ
  • Publication type: 12m petition finding
Item 11

Listing

Dec 2, 2016

Dec 2, 2016 Listing
Review of Native Species That Are Candidates for Listing as Endangered or Threatened; Annual Notificโ€ฆ
  • Publication type: CNOR
Item 12

Listing

Oct 10, 2019

Oct 10, 2019 Listing
Review of Domestic and Foreign Species That Are Candidates for Listing as Endangered or Threatened;โ€ฆ
  • Publication type: CNOR
Item 13

Listing

Aug 26, 2021

Aug 26, 2021 Listing (Endangered)
Endangered and Threatened Wildlife and Plants; Endangered Species Status With Critical Habitat for Gโ€ฆ
  • Publication type: Proposed
Item 14

Critical Habitat

Aug 26, 2021

Aug 26, 2021 Critical Habitat
Endangered and Threatened Wildlife and Plants; Endangered Species Status With Critical Habitat for Gโ€ฆ
  • Publication type: Proposed
Item 15